Sometimes Vector is better; sometimes ArrayList is better; sometimes you don't want to use either. I hope you weren't looking for an easy answer because the answer depends upon what you are doing. The key difference between Arrays and... Read More

JAVA Interview Questions and Answers,JAVA Faqs,JAVA Interview FAQs and JAVA Books,JAVA interview ebook,JAVA technical interview questions,JAVA Quiz,JAVA Interview Paper,JAVA Placement Papers,JAVAInterview Procedure,JAVA Aptitude Questions,JAVA... Read More

In java there is no multiple inharitence. So if we extend thread class, we can not extend some other. If we use Runnable interface. We can implements any no. of interface. Thread class is implemented from runnable interface. Runnable has only... Read More

Question : can we write return statement in try catch or finally block. suposse we write return 0 in try catch or finally. can we do.  Answers: Yes,We can write the return statement in try catch & finally. The only thing is that... Read More

You have to use array of Object to store the element and then provide the functionality of adding,seraching and removing the element.This is the way you can create your own arrayList without using Collections. Read More

Generic Servlet class is a base class that specifies the class structure for protocol independent servlet and acts as a base for different servlets. HttpServlet is a servlet that extends Generic Servlet and is specialised to work on HTTP... Read More

If JVM is present then it converts .java code into .class(bytecodes) hence platform independent. But not garbage collection and thread technology is platform independent Read More

By using the operator overload have lot of problems is there. even some time the programmer get coufused. and its increase the complexity of the program. for that purpose only its removed in java. Read More

Main() and Main() are two different methods in Java. But if u write Main() instead of main() then there will no exception at the compile time. But It will generate a runtime exception : java.lang.NoSuchMethodError: main Read More

6.what is single inheritance. ans:one class is inherited by only other one class 7.what is multiple inheritance. ans:One class inheriting more than one class at atime 8.can java support multiple inheritance. ans:No 9.what is... Read More

HashMap will not store the elements in order.Whereas TreeMap stores in order.so while retrieving we will get in a particular order.But for HashMap we won't. Read More

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The Java Language the referencing and dereferencing of objects is handled for you automatically. Java does not allow you to manipulate pointers or memory addresses of any kind. It does not allow you to cast object or array references into integers... Read More

Most multi threaded applications involve several threads, Threads need stack and heap space, and, depending on the platform, thread creation can be expensive. In addition, cancellation and shutdown of threads can be difficult, and a well-designed and... Read More

Marker interface example- public interface Serializabale {} public interface Cloneable {} Also known as 'Tagging' interface Read More

The java.util.EventObject class is the highest-level class in the event-delegation class hierarchy. Read More

Observer is an object that wishes to be notified when the state of other object changes.(Listener,registered with the source to be notified of any change in the source) Observable is an object whose state may be of interest and in which other... Read More

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The Hotspot VM is a collection of techniques, the most significant of which is called "adaptive optimization. The original JVMs interpreted bytecodes one at a time. Second-generation JVMs added a JIT compiler, which compiles each method to native... Read More

Java don't support Multiple Inheritance. For that we can use Interface. Interface is like the getway to comunicate between to classes. Not always we write methods in Interface, we can also create objects in the Interface. The Object which... Read More

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Question : Given A = 1, B = 2, C = 3, D = 4 ?? Z = 26, write a java standalone program to encode the word ?TELEPHONE? into numbers. Answers: class enCode { public static void main( String ar[]) { String enCodeWord = ... Read More

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The primitive datatypes are nothing but the basic data types..like int,char,float,double etc..Char is a datatype which stores 2 bits of data..String has been derived from Char which takes more number of Char and integers..providing the more memory... Read More

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null interfaces are nothing but marker interfaces which doesn't have any methods. The purpose is which tells to JVM for certain functionality like serializable, Cloneable etc are the examples Read More

A high cohesion and low coupling is always desired. Cohesion is closely related the various functions of a class. Coupling is how closely this class is integrated with implementations of other classes, that a change in any other class will result... Read More

Yes, there are seperate stacks. Threads share memory area, but have different stacks. http://www.particle.kth.se/~lindsey/JavaCourse/Book/Part1/Supplements/Chapter08/processorView.html Read More

Callable statement is that which can be called anywhere in the program. Eg:- getText() Prepared statement is that which is coded with a certain procedure and execute when the program gets executed. Read More

public class ArrayList extends AbstractList implements List, RandomAccess, Cloneable, Serializable Resizable-array implementation of the List interface. Implements all optional list operations, and permits all elements, including null. In... Read More

Reflection is a feature of the Java programming language. It allows an executing Java program to examine or "introspect" upon itself, and manipulate internal properties of the program Read More

Overloading is resolved at compile time and overriding is resolved at run time. Read More

length() is function which is defined for string class whereas length is used only for array. Read More

Transient variable can't be serialize.A volatile variable is not allowed to have a local copy of a variable that is different from the value currently held in "main" memory. Read More

PreparedStatement: Actually "PreparedStatement" is an interface in the JDBC API. The functionality of this statement is "Executing the SQL queries in the database.This statement is having the "pre-compiled code" ,so it reduces the compilation... Read More

Question : Strings are immutable.But String s="Hello"; String s1=s+"World"; S.O.P(s1); means printing "HelloWorld".How ? Answers: String is immutable means that : Say s = "hello" would point to certain location , say... Read More

Question : if two overloaded methods are- Test(Object xyz) and test(Customer cust)[Assume Customer is a class with member name of type String].Now if we call test(null), which method will be called? why?           ... Read More

To use jni we need three things one a native library , usually a ". DLL" which is complied in C or C++. a header file for the native library and the java code whre native aPI implementation is called. a method that calls the native librbary... Read More

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see the suns source code . Read More

Concat is used to add a string at the end of another string.But append() is used with String Buffer to append character sequence or string.When we concatinate a string with another string a new string object is created.But in case of StrinBuffer... Read More

Cookie:Cookie is nothing but small texual peace of information send by the server .Normally cookies are used to maintain session tracking .Cookies are stored in the client machines.But all browsers does not support cookies. Submitted by... Read More

A call made to repaint() method would wipe off the existing graphics on the applet and call the paint() method whereas this is not the case with calling paint() method directly. Submitted by Arun Pasuparthi (Arun_Pasuparthi@satyam.com) Read More

When you use Serializable interface, your class is serialized automatically by default. But you can override writeObject() and readObject()two methods to control more complex object serailization process. When you use Externalizable interface, you... Read More

Question : What are the different types of Synchronization? Is there any other way of method or class or object locking       Answers: Synchronization is using two ways 1) Method Synchronization example:... Read More

Both throw and throws are keywords. throw is used to explicitly throw a user defined or predefined exception. throws is used when dont want to handle the exception and just specify that what all exceptions the method might throw. syntax : ... Read More

1.ArrayList os not synchronized whereas the Vector is synchronized. 2.Arraylist is faster whereas Vector are slower in processing. 3. Elements in the arraylist can be traversed using Iterator interface whereas in the case of Vector we can... Read More

25 MHz =25*10power(6) cycles/second i.e.for 3 clock cycles, time = 3/25MHz = 120 nano sec Read More

Widning and Narrowing will appear in the Casting operation. Widning is nothing but converting lower datatype to higher datatype when we cast the datatypes.Narrowing is nothing but converting higher datatype to lower datatype when we cast the... Read More

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Servlet Lifecycle: init() ->this initalizes the servlets initialization information with the configuration parameters. service : here the business logic starts. that is, all the request and response services goes here. destroy() : once... Read More

JVM is an abstract computing machine like any other real computing machine which interprets the byte code( .class file which contains virtual machine instructions ) to a machine dependent native code. The output of JVM i.e the native code... Read More

August 19th, 2009 by sd | Posted in Uncategorized<br><br>Overloading is the practice of supplying more than one definition for a given function name in the same scope. The compiler is left to pick the appropriate version of the function... Read More

If this thread was constructed using a separate Runnable run object, then that Runnable object's run method is called; otherwise, this method does nothing and returns. Subclasses of Thread should override this method. Read More

(1)Applications are must run inlocal machine where as Applets needs no explicit installation on local machine. (2)Applications mustbe run explicitly within a JVM where as Applets loads & runs itself automatically in a java-enabled browser.... Read More

SERVERS ARE TWO TYPES: 1)WEB-SERVER 2)APPILICATION SERVER. Tomcat is a web-server,this is 3-tier Architecture. where as Weblogic is an Application Server,this is n-tier Architecture.In Tomcat we cannot deploy an EJB.but in Weblogic we can.... Read More

Throw as well as Throws they sound similar but there is diff among them.Both of them are keywoeds used in JAVA and are related with exceptions. THROW - this keyword is used to throw an exception explicitly. -for eg consider we catch an Divide... Read More

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Interupt is the method on the thread to distrub or interupt on the other thread which are under execution. Where as the join method is used to say t.join() is to suspend the current thread operation for a time being and go to the other thread and... Read More

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Difference b/w the Hashmap and Treemap: Both Hashmap and Treemap are datastructures, which holds the values of in the form of key -value pairs.Both are unchronized datastructures. but difference is hashmap is a unordered datastructure,treemap is... Read More

The JavaMail API provides a platform-independent and protocol-independent framework to build mail and messaging applications. Submitted by Siju Kurian (siju.kurian@wipro.com) Read More

Final class: Final class is class ,which should not inherited into the derived class. If a class declared as final by defaulat all methods are final not fields. You can't change the final class object. eg:String, Date, System.Math etc. ... Read More

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java.rmi.Remote java.util.EventListener Read More

Ananymous classes are useful when you want to extend more than one class at a time ( Java doesn't support )and also it doesn't require next time. Ex: Frames with ananymous classes for handiling the events with in a same program. Read More

yes, It cam be overloaded, I am not sure if it can be overridden. In over loading u have same method name with different parameteres. So main can have no params or it can have a String objects as arguments. The purpose of passing string as args... Read More

A while statement checks at the beginning of a loop to see whether the next loop iterationshould occur. Ado statement checks at the end of a loop to see whether the next iteration of a loop shouldoccur. The dostatement will always execute the body... Read More

Object oriented programming languages directly represent the real life objects. The features of OOPL as inhreitance, polymorphism, encapsulation makes it powerful. Read More

If you are running Java on English Windows platforms, it is probably Cp1252. If you arerunning Java on English Solaris platforms, it is most likely 8859_1.. Read More

Ya u can limit the initial capacity we can construct an empty vector with specified initial capacity public vector(int initialcapacity) Read More

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A reference variable or constant declared as 'final' has a value that is immutable and cannot be modified to refer to any other object than the one it was initialized to refer to. Thus the 'final' specifier applies to the value of... Read More

Iterator is returned by List and other Collection interfaces. Iterator is fail fast if a modification to the collection is performed while iterating. Enumeration is used by Vector and Hashtable. Enumeration may or may not throw an error if the... Read More

Question : JVM is platform independent/dependent?why? 2) which one is faster in execution Array List or Array? why? Answers: JVM is platform dependent. Just think u don' t use a unique jdk for each operating system.... Read More

 upward casting small datatype is casted in to big data type such as byte is casted as int type.but in downward casting the big data type is casted into small data type such as long is casted into int or byte. Read More

attribute - is a member of a class parameter - is a member of a method signature argument - is used to send values to the method from the caller. parameter - is a place holder for the incoming values for a method from the caller. Read More

An abstract computing machine, or virtual machine , JVM is a platform - independent execution environment that converts Java bytecode into machine language and executes it. Read More

JVM is basic run time environment for java applications. Where all java objets birth,live and dead. Read More

A catch clause can catch any exception that may be assigned to the Throwable type. This includes the Errorand Exception types. Read More

Yes, why not? It's just a class with methods just like any other class. Read More

The following some information regarding the question: The information was taken from (http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=1&t=000875) written by sasikala kumaresan A unicast packet is the complete... Read More

Soft Reference :--> An object is softly reachable if it is not strongly reachable and there is a path to it with no weak or phantom references, but one or more soft references. The garbage collector might or might not reclaim a softly reachable... Read More

The following link has discussion about static variables being garbage collected. The last posting in the discussion gives a lot of relevant information. http://www.codeguru.com/forum/printthread.php?t=362966 justAnother Read More

We do implement a interface when we want to add a specific characteristic to a class like if we want a particular human being is a singer then we can implement the singer interface to add this characteristic to a particular person.Interface... Read More

Single inheritance, multilevel inheritance and hierarchial inheritance is allowed in java. Muliple inheritance and hybrid inheritance is not allowed because implementing these in Java will cause data duplication and ambiguity. The derived class... Read More

When you synchronize on an object your thread gains exclusive use of that object until synchronization ends or wait is called on the object. Language support for synchronization: 1. Use the synchronized block: In a method you may: synchronized... Read More

The cloneable interface is provided by java for the classes that want to suporrt the function clone or want to override it. This function is supposed to to create and return the copy of an object. Read More

A break statement results in the termination of the statement to which it applies (switch, for, do, or while). A continue statement is used to end the current loop iteration and return control to theloop statement. Read More

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THERE IS ONE MAJOR DIFFERENCE IN COMMANDLINE ARGUMENTS OF JAVA AND C.LET US ASSUME THERE IS AN EXECUTBLE FILE NAMED"COPY. EXE", WHICH SOURCE CODE IS IN C AND TAKES 2 COMMANDLINE ARGUMENTS THEN WE WILL RUN IT AS SHOWN BELOW C:>COPY SOURCE,DEST -... Read More

JVM is java virtual machine which should be there on an operating system for any java application to be run on.so, it depends on how many operating sytems you have on your system installed. if you want the JVM installed on all the operating systems... Read More

The File class encapsulates the files and directories of the local file system. The RandomAccessFile classprovides the methods needed to directly access data contained in any part of a file. Read More

Type 1: JDBC-ODBC Bridge plus ODBC Driver: The first type of JDBC driver is the JDBC-ODBC Bridge. It is a driver that provides JDBC access to databases through ODBC drivers. The ODBC driver must be configured on the client for the bridge to work.... Read More

instanceof is used to check to see if an object can be cast into a specified type without throwing a cast class exception. isInstance() determines if the specified object is assignment-compatible with the object represented by this Class. This... Read More

Synchronization occurs when you want two threads to run, but they are somewhat dependent on each other. A thread is a distinct flow of program logic that can be executed at the same time as other threads. This make it seem like two things are... Read More

Web server for running the servlets:Mainly to run the servlets we will use Apache Tomcat sever,Sunone Studio.(websevers).But servlets also run in the Application server such as Weblogic,websphere,Jboss. Submitted by Chinnakotla Devarathnam ... Read More

Java: There are no pointers. There is no Operator Overloading. There are no preprocessors. There are no Structures and Unions. There are no Enums. There are no Functions (only methods within class). There is no goto statement.(In java goto and... Read More

The readLine() method returns null when it has reached the end of a file. Read More

The wait(), notify(), and notifyAll() methods are used to provide an efficient way forthreads to wait for a shared resource. When a thread executes an object's wait() method, it enters the waiting state. It only enters the ready state after... Read More

MenuItem. Read More

The stop(), suspend() and resume() methods have been deprecated in JDK 1.2. Read More

An Object May not have a class defination eg int a[] where a is an array An Instance Should have a class defination eg MyClass my=new MyClass(); my is an instance Read More

by using init() methd applet method can be initiaized Read More

Collecting the objects taht are no longer used. java uses System.gc() method or Runtime.gc() method here Read More

Question : Addition of two numbers using Bitwise operators. Reading An 2D array using single for loop          Answers: this is power of 2 without using any operator and any math function class power { ... Read More

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INPUT TAG WITH TYPE (FILE) Read More

I have an idea. But I am not sure if it is the right answer. Can I divide these 4 methods into 2 interface? Then I can only implement the wanted 2 methods. Read More

There are so many examples behind this reason. a. Code written using AWT and compiled on windows machine will not run on Unix, since Windows is a graphics rendered environment and unix is not, so will have to provide some XManger to render the... Read More

The Class class is used to obtain information about an object's design. Read More

Singleton is one and only one instance of a Class for a class loader, which is used by all users of application. Public class Singleton { Singleton singleton = null; private Singleton () {} // Inportant public static Singleton... Read More

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The methods to over ride are equals() and hashCode(). Read More

when more than two task are permorming under a singel process,is known as multithreading Read More

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Any Vector methods acsess which operate on data is Synchronized. Read More

Java Remote Method Invocation (Java RMI) enables the programmer to create distributed Java technology-based to Java technology-based applications, in which the methods of remote Java objects can be invoked from other Java virtual machines*,... Read More

<% String str = "123"; %> <script> function f() { alert('<%=str%>'); } </script> I am not sure if the above code works. The better way could be to send the java values to the... Read More

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All applets have the following four methods: public void init(); public void start(); public void stop(); public void destroy(); Read More

Mutable string means we can append to that string.example StringBuffer object is mutable string.String is immutable object when we declre String="abc"; a string object abc with fixed length is created.We cant add anything to it .If we do java... Read More

We can pass values to servlet from HTMLpage using "request.getParameter(string);" method.Which is a method in the HttpServletRequest interface. Submitted by chinnakotla devarathnam (devarathnam@yahoo.co.in) Read More

Java is a object-oriented programming language which is platform neutral. That is unlike C or C++ java programs, Java can be run on any operating system with its JVM. J2EE is just a specification for server side programs. That is to support... Read More

Two methods may not have the same name and argument list but different return types. Read More

JAR file stands for Java ARchive, a compressed file like zip, rar, lha files. Using the jar command, a JAR file is commonly used for packaging Java classes (.class). Submitted by Tsar Primo Geronimo (tsar2020@hotmail.com) ________________ ... Read More

Frame. Read More

The values true and false are not keywords. Read More

The null value is not a keyword. Read More

To handle data in the form of text the abstract classes:Reader and Writer are used. in this Print reader/writer handle printing of characters on the screen or on the printer. Streams represents IO devices.by using streams to handle IO devices.by... Read More

CGI creates process for each client call where as servlet creates process for the first time and then uses thread for each client. Submitted by Sunanda Yugandhar (sunanda.yugandhar@aspiresys.com) Read More

Abstraction means to hide the unnecessary data so we use for that abstract class or abstract methods. EX:abstract class car { abstract void fun() {} } Read More

When an exception is thrown within the body of a try statement, the catch clauses of the try statement are examined in the order in which they appear. The first catch clause that is capable of handling the exception is executed. The remaining catch... Read More

Servlet: Servlet is java web application component.or a java program which implements the Servlet interface.The duty of servlet is as follows: 1. Retriving the client request. 2. Processing the client request. 3. Generate the response w.r.t client... Read More

The purpose of the Runtime class is to provide access to the Java runtime system. Read More

The sizeof operator is not a keyword. Read More

The prefix form performs the increment operation and returns the value of the increment operation. The postfix form returns the current value all of the expression and then performs the increment operation onthat value. Read More

Serializable Interface :It is a marker interface ,which does not contain any methods and constants.But it is used for protocol purpose. Submitted by Chinnakotla Devarathnam (devarathnam@yahoo.co.in) Read More

The enableEvents() method is used to enable an event for a particular object. Normally, an event is enabledwhen a listener is added to an object for a particular event. The enableEvents() method isused by objects that handle events by overriding... Read More

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java.util.Concurrent ( Queues) Read More

Depends on the definition of " fully object oriented programming".There is no such term in Java World IMHO. Read More

The comparable interface should be used when the current object is to be compared to objects of its type only. The comparator should be used when some external class is taking your class as a parameter for some comparison operation and it doesn'... Read More

Definitely we can make a method final, without making the whole class as final. ex: public class MyClass { private String name = "Ram"; public String getName() { return name; } final void display(String str) { System.out... Read More

A layout manager is an object that positions and resizes the components in a Container according to some algorithm; for example, the FlowLayout layout manager lays out components from left to right until it runs out of room and then continues... Read More

Abstract class: Abstract class can contain abstract methods and concreat methods (implementatioin methods). Interafe : An Interface contains only abstract methods(not concreate methods). Submitted by Devarathnam.C (devarathnam@yahoo.co.in) Read More

Reflections are basically used to find the details of a class based on the object . Read More

Question : Solve it... public class test { public static void main(String[] args) { int i=5; i=i++; System.out.println("result::"+i); } } The result wil be 5..!! and not 6 why??? Answers: i=i++ can be... Read More

Stream Reader A Stream Reader is a bridge from byte streams to character streams: It reads bytes and translates them into characters according to a specified character encoding. The encoding that it uses may be specified by name, or the platform&... Read More

The Java Memory Model defines how threads interact through memory. Read More

The main disadvantage of thread is that we need to synchronize the object while using the thread Read More

A Scrollbar is a Component, but not a Container. A ScrollPane is a Container. AScrollPane handles its own events and performs its own scrolling. Read More

JIT- just in time compiler Yes, it comes along with the java kit, actully it compiles the program. Actully the interpreter converts the high level lanhuage into machine level language, one by one. Since the java has a lot of run time... Read More

Serialization is the state of write the object in the byte stream transient r applied to the variables the value cannot be persisit when the object r stored Read More

java doesnt support pointers as its a tedious job to locate memory as in c++.one of the major problem in most oops languages is to handle memeory allocation.programmer had to explicitely handle memory for the programs max utilization.java doesnt... Read More

ServletConfig is assosiated with Servlet Where as ServletContext is assosiated with Web Application(or context path). Come 2 DD(web.xml) perspective, The data In <init-param> tag is specific 2 that perticular servlet.u can use that... Read More

 i think Core java is more specific to the OOP concepts and it. Java covers a much picture like J2ee technologies/specifications which by itself is huge. Read More

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Array is the collection of Similar data type and has fix size. datatype arrayname[]=new datatype[size]; or datatype []arrayname=new datatype[size]; eq: int a[]=new int[10]; Two Dim Array: datatype arrayname[][]=new datatype[rows]... Read More

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Because when u r using a particular layout manager it ues full fram for work you can use gridbag layout for this purpose Read More

 Canvas is a component represents a blank rectangular area of the screen onto which the application can draw or from which the application can trap input events from the user. Read More

There are 2 reasons that i can think of: 1. java support for primitive data type 2. no direct implementation of multiple inheritence Howerver java has a way out of these two issues in form of: 1. wrapper classes 2. interfaces Read More

The thread can be created either by extending the Thread class or implement the Runnable interface. Read More

No, Combination of modifiers final and abstract is illegal in java. Submitted by Rama Krishna ( iamvemuri @ yahoo . com ). Read More

The high-level thread states are ready, running, waiting, and dead. Read More

Error occurs at compile-time, while exception occurs at run-time. Read More

String objects are constants. StringBuffer objects are not. Read More

By quickly switching among executing tasks, it creates the impression that the tasks execute simultaneously. If it didn't switch among the tasks, they would execute sequentially. Read More

The result is a String object. Read More

Question : 1)What are the actual functions of JVM? 2)When to use a class and when to use an Abstract class? 3)what is the use of constructors other than creation of objects? 4)when to use constructors? 5)when to use Interface? 6... Read More

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There is no concept of "destructors" in java.Java supports this specility by introducing the "GarbageCollector".The Garbagecollector is under the control of the JVM.JVM runs the Garbagecollector periodically basing on "mark and sweep" algorithms.U... Read More

Thanks in advance.i want to move a JButton using Mouse in runtime within a JFrame.saran Read More

Try / catch is used to guard against possible errors or problems. At the minimum the error should at least be reported to the user or logged in some way. More advanced systems will attempt to recover from the error and continue with normal operation.... Read More

The abs() method is used to calculate absolute values. Read More

I think this is the one of the way to return two refference fro one Object ClassA extends from ClassB then in ClassB we can write like this ClassB b=new ClassB(); this is one and ClassA a= new ClassB(); this is two of... Read More

The main difference: Javabean is a reusable s/w component that can be developed & run within a single system. EJB is used in distributed environment. EJB is developed in one node made to run in any system. Read More

The null interface is also called as Marker Interface. EX:In J2EE applications,if u want to make any servlet as thread safe,then we make as such,through the SingleThreadMarkerInterface. For this ur servlet just need to implement this... Read More

You just need to implement the Interface Serializable and don't have to implements any methods.This is because Serialiazble Interface has no methods.Its just a Marker/Tag Interface which tells that this object is serilizable. Read More

An object's finalize() method may only be invoked once by the garbage collector. Read More

An unreachable object may become reachable again. This can happen when the object's finalize() method is invoked and the object performs an operation which causes it to become accessible to reachable objects. Read More

A class with no restriction on accesors , mutators or constructor can be considered as a plain Java class.Java Bean is a spl java class with accessors(getters) and mutators(setters) for the instance variables present.Moreover, it can only have a... Read More

Class variable are class member which are used in the class and instance variable is a object of that class to be used to access methods of that class. Read More

An anonymous class may implement an interface or extend a superclass, but may not be declared to do both. Read More

JApplet is actually a subclass of Applet, so JApplets are in fact Applets in the usual sense. However, JApplets have a lot of extra structure that plain Applets don't have. Read More

Total 5 are there:1.Flow layout.2.Boarder Layout 3.CardLayout 4.GridLayout. 5.FlexGridBagLayout.1.Flow:its defalut layout,it can arranged left to right.2.Boarder:its arranged North,West,South,East order.3.Card:it follows deck of cards(like playing... Read More

The garbage collector invokes an object's finalize() method when it detects that the objecthas become unreachable. In java u can access the data through objects.Here Object class is a super/base/parent class for all the java classes,so it... Read More

Two thread communicate using the notify, notifyAll and yield methods provided in the Runnable Interface. Read More

An inner class without naming is called an anonymous class Read More

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Because from any constructor of the subclass first a call is made to super() unless you specifically make any super call with args() eg super(arg1,arg2). Read More

Session is used to maintain state of the user bcz Http is stateless protocal. HttpSession class is used to create a session for an application. Read More

Enumeration and Iterator both are interfaces present in util package. Enumeration is a legacy interface which does not come under the collection framework, wheras Iterator is an interface present in the collection framework. All the legacy classes... Read More

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The AWT toolkit is an interface between the abstract window layer and a specific windowing implementation. Read More

This example creates a hashtable of numbers. It uses the names of the numbers as keys: Hashtable numbers = new Hashtable(); numbers.put("one", new Integer(1)); numbers.put("two", new Integer(2)); numbers.put("three", new Integer(3)); To retrieve... Read More

String objects are immutable. Well let me explain taking an example:Look at the code below along with the comments:String test = " Java"; // Create a string object "java" and assign a reference 'test ' to it.String test2 = test; //create... Read More

ServerSocket is a class for creating a server side connection for remote clients to connect to, On client connection success, returns an ordinary socket which can later be used to communicate with the client. For a connection to be created it... Read More

using public void init() method Read More

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The Main disadvantage of threads is : Threads is operating system dependent. Read More

Wrapped classes are classes that allow primitive types to be accessed as objects. Read More

System.out.println();incase System is a class in java.lang package.And out is the static field in the java.lang.System class. It works by a native method. Read More

Window, Frame, Dialog, FileDialog, Panel, Applet, or ScrollPane. Read More

The java designer's view was to develop a simple, object oriented, and familiar language. In the designers' opinion, multiple inheritance causes more problems and confusion than it solves. Read More

This is another of the data-driven pattern. The client invokes a particular module using a command. The client passes a request, this request gets propagated as a command. The command request maps to particular modules. According to the command, a... Read More

your future is going to be doomed. Read More

A pure Object Orientad Language is which implements All the OOP concepts. Java doesn't support Multiple Inheritance & Operator loading thats why "Java is not 100% pure Object Language". C# is a pure OOP Language. Read More

create new object otherthan using new operator in java ObjectType obj = className.getMethod(); above coding obj is object return by method getMethod Read More

When a window is repainted by the AWT painting thread, it sets the clipping regions to the area of the window that requires repainting. Read More

Iterator :--- Iterator takes the place of Enumeration in the Java collections framework. One can traverse throughr the the collection with the help of iterator in forward direction only and Iterators allow the caller to remove elements from the... Read More

For struts we use struts-config.xml, web.xml. and for ejb we normally use ejb- jar.xml, deployment descriptor also in xml form. Read More

Commas are used to separate multiple statements within the initialization and iteration parts of a for statement. Read More

In array list we can save only objects by using the method add(Object).if we can we save primitive data types in array list ,then wrap the primitive value to its corresponding Wrapper class then add that object to the array list.after retrieving the... Read More

If a checked exception may be thrown within the body of a method, the method must either catch the exception or declare it in its throws clause. Read More

Unicode requires 16 bits and ASCII require 7 bits. Although the ASCII character set usesonly 7 bits, it isusually represented as 8 bits. UTF-8 represents characters using 8, 16, and 18 bit patterns.UTF-16 uses 16-bit and larger bit patterns. Read More

In java deallocation is handled automatically.When there is no reference to an object exists, it means the object is no longer needed then the object is destroyed automatically is called garbage collection.Garbage collection only occurs... Read More

A StringTokenizer is utility class used to break up string. e.g. StringTokenizer st = new StringTokenizer("Hello World"); while (st.hasMoreTokens()) { System.out.println(st.nextToken()); } Output: Hello World Read More

The Collections API is a set of classes and interfaces that support operations oncollections of objects. Read More

You can check Runtime r = Runtime.getRuntime() ;r.freeMemory() ;before and after the creation of the new Object you can check the memorty and by subtraction u can get the used memory. Not accurate but useful. Read More

Java supports "low-level" and "high-level" classes. "Low-level" classes provide support for socket programming: Socket, DatagramSocket, and ServerSocket classes. "High-level" classes provide "Web programming": URL, URLEncoder, and URLConnection... Read More

Java uses layout managers to lay out components in a consistent manner across allwindowing platforms.Since Java's layout managers aren't tied to absolute sizing and positioning, they are ableto accomodateplatform-specific differences... Read More

Collection: Collection is an interfact within in collection framework.collection framework provides many interfaces likes collection,maps,etc.list and set both are the interface and both interface implement collection interface. Read More

Question : Given two tables Student(SID, Name, Course) and Level(SID, level) write the SQL statement to get the name and SID of the student who are taking course = 3 and at freshman level.          Answers: ... Read More

Finally block will be executed first before the exception is propagatged to the next level up. Read More

Once an object is garbage collected, it ceases to exist. It can no longer become reachable again. Read More

Add two variables and assign the value into First Variable.Subtract the Second value with the Resul Value. and assign to Second Variable.Subtract the Result of First Variable With Result of Second Variable and Assign to First Variable.EX:Int a=5,b=10... Read More

Difference b/w RMI AND CORBA: RMI(Remote Method Invocation ),CORBA(Common Object Request Broker Architecture) both are specifications or technologies,which are used in the Distrubuted environment. RMI is a language dependent ,but platform... Read More

If there is a functionality (like employee) that is common across specific classes, then specific classes (Hourly Employee) can be inherited from the common class. What if there is no common functionality, but there is a common contract that classes... Read More

The JavaTM Archive (JAR) file format enables you to bundle multiple files into a single archive file. Typically a JAR file will contain the class files and auxiliary resources associated with applets and applications. Read More

Byte code is the output of java compiler. Unlike C,C++ which produce executable code after compilation,java compiler generates byte code which is platform independent. JVM interpretes this byte code and generates native/machine code which is... Read More

Java language runs on a virtual machine, it runs somewhat slowly compared to other programs. It is difficult to write a perfect program, especially if it is as big as a virtual machine Read More

A field variable is a variable that is declared as a member of a class. A local variable is avariable that is declared local to a method. Read More

An Exception can be caught and recovered: ArrayIndexOutOfBoundsException means you tried to access a position of an Array that does not exist - no big deal. An Error is unrecoverable: OutOfMemoryError means that the JVM has no more memory to... Read More

J2EE stands for Java2 Enterprise Edition it is not a single technology it comprise many technology, J2EE is an specification used to build web application Read More

Question : what happens if we execute the program? class Return{ int display(){ try{ return 1; } finally{ return 2; } } public static void main(String args[]){ Return r=new Return(); r.display(); } }   ... Read More

FileReader FR = new FileReader("C:/input.txt"); BufferedReader reader = new BufferedReader(FR); //Used for reading line by line while( (reader.readLine())!=null) { //Write ur logic here } Read More

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Server side programming used to improve file dowloading performance, it hendles the server. Read More

Hashtable and HashMap both are Key Value pairs and they function both the same way except in sychronization and HashMap accepts one null Key and many null values. HashMap can be synchronized by Map m = collections.synchronizeMap(hashMap); Read More

transient,volatile,final,static transient 9for variable):-- variable's state can't be serialized. final:-- can be declared for class,METHODS as well as variables, who's definition can't be changed. static :-- variable ... Read More

Regarding use of equals on StringBuffer and String : Since StringBuffer diesn't override equals therefore such a comparison will always give false in case of StringBuffer. Read More

Static Method shld be minimised in Java Programm.For Ex . if i am m accessing any method and request modified the object then when other request comes it wll met to modfied Object.So we shld minimise the Static method in Java program as Original ... Read More

If you override equals() method and say { return false; } , even same objects will not be equal. If that was not the trick question the interviewer meant, then I think that if there are two different objects, even though they may have same values... Read More

The Reader/Writer class hierarchy is character-oriented, and the InputStream/OutputStream class hierarchy is byte-oriented. Read More

int, float etc are primitives not objects so that part is ruled out. String s= "hello" is a valid way other valid ways include reflection also by using methods that return new objects Date d= Date.getInstance(); Toolkit tk= Toolkit... Read More

A class is a subclass of itself. Read More

JAVA is fully Object oriented language. It has two phases first one is Compilation phase and second one is interpratation phase. The Compilation phase convert the java file to class file ( byte code is only readable format of JVM) than... Read More

An interface may be declared as public or abstract. Read More

A string buffer implements a mutable sequence of characters. A string buffer is like a String, but can be modified. At any point in time it contains some particular sequence of characters, but the length and content of the sequence can be changed... Read More

setEditable(). Read More

Struts is a framework provided by Apache group. It uses MVC2 model architecture. It is overcoming the drawbacks of old MVC model. If we use Struts in our application development, there is no need of creating any ActionServlet. Struts framework will... Read More

1)boolean 2)int 3)float 4) byte 5)short 6)char 7)long 8)double Read More

Primary Advantages is, we don't need to add code in Java Class(attribute, Mutator Method[get/set]), Sipmply we can add new attributes by modifying XML files. Eg . ActionForm and DynaActionForm in Struts FrameWork. Read More

Question : Imagine there is a class Employee. We create an object of Employee Employee a= New Employee(); If we are giving System.out.println(a); What gets printed?      Answers: It calls the toString() method of the... Read More

An object is subject to garbage collection when it becomes unreachable to the program in which it is used. Read More

According to Java in a Nutshell, 5th ed boolean, byte, char, short, long float, double, int Read More

Strings are not dynamically growable but String buffer is dynamically growable Read More

ArrayList can not be synchronized because in synchronization the same data at the same time can access with out data loss or data corruption but in ArrayList it is not possible. Read More

You can not change the background colour of DOS prompt by java. You can change the DOS prompt colour by changing the settings of DOS prompt.(click on the properties->Color from DOS prompt screen). Read More

No answer available currently. Be the first one to reply to this question by submitting your answer from the form below.   Read More

v The super class for exception is java.lang.throwable divided into two types: 1.java.lang.exception 2.java.lang.error Read More

The EventObject class and the EventListener interface support event processing. Read More

Runtime polymorphism is the concept of identifying the object reference at run time.This is also called as Late/Dynamic Binding in C++. The following example explains you how it works. class SuperHandler { public String handleRequest() { return... Read More

The following files will be generated: My.java MyHelper.java MyHolder.java MyOperations.java _MyStub.javal Read More

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According to Java null is a key word literal. So are true and false.They cannot be used as variable names even though they are not keywords. Read More

We not define the constructor of super class in subclass because when we extend the class then property of superclass come in subclass.. Read More

Question : If my java based application is hanging once in a while. Where would you start looking at the problem, what changes can you do? My application has a builtin Ldap client and is communicating with a Ldap server. now having a... Read More

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If a server object is not loaded in the memory and the request for it comes, then the server object is loaded in to the memory and is initialized. Read More

no, we can do this by response.sendRedirectUrl("path"); Read More

we can create object at runtime using object using class.forname.using class.forname we can load specific class and after that we can create a instance of that class using newInstance method. Read More

JRE stands java runtime invironment. JAR file is a compressed java file. Read More

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virtual function can be understood only from a design viewpoint. Virtual means existing inappearance but not in reality.When virtual function are used , aprogram that appears in reality be calling a function of a different class Read More

The default value of the boolean type is false. Read More

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Program threads are not created at compilation and at the time of execution of java program. Thread.activeCount() gives the no. of active threads. Read More

AWT: Abstract window toolkit(AWT) is a non-peerbased technology.The AWT components fully dependent on the underlaying platform. SWING: Swing is a not replacement technology of AWT.But swing allows u lightweight components with peerbased technology... Read More

You would create interfaces when you have two or more functionalities talking to each other. Doing it this way help you in creating a protocol between the parties involved. Read More

Java is not a fully object oriented language because it does not support multiple inheritance directly.But it does so by using theconcept of interfaces. A language is said to be fully object oriented if it supports classes,objects,inheritance and... Read More

Singleton class is a class whose only one object can be created at a time. - To achieve this one method is that we make its constructor private and provide a static method that returns its instance. When a Singleton class is garbage - collected... Read More

Public : Any other class from any package can instantiate and execute the classes and methods. Protected : Only subclasses and classes inside of the package can access the classes and methods. Private : The original class is the only class allowed... Read More

You cannot inherit a constructor. That is, you cannot create a instance of a subclass using a constructor of one of it's superclasses. One of the main reasons is because you probably don't want to overide the superclasses constructor,... Read More

Java is multi platform-> Platform Independent Language, so its used widely in very big softwares or games where multiple variables needed. To Differentiate among that huge no of variables,,Java is Case Sensitive. Read More

InputStream and its sub classes are used for reading data in the form of streams. Ex : FileInputStream, DataInputStream OutputStream and its sub classes are used for writing data in the form of streams. Ex: FileOutputStream, DataOutputStream... Read More

Yes, we can call a application from another application for example in a web application we can call a document and read the data from it like that we can call some other aplication to run in a action Read More

 package is a grouping of related types providing access protection and name space management. Note that types refers to classes, interfaces, enumerations, and annotation types. Enumerations and annotation types are special kinds of classes and... Read More

All the Mehods in HashTable are synchronized whereas HashMap is not thread-safe. Another big difference is that HashMap allows null key and null values whereas HashTable does not permit null key and null values. Submitted by Bikramjit Bardhan ... Read More

You should use the word synchronized to mark the critical section of code. You may also use other methods of thread synchronization (see wait(), notify(), notifyAll() etc. Read More

We CaNNOT override a static method. See a static method has nothing to do with the instance of the class. So when u r using a static method using .(dot) it actually subsitutes the class name. Inheritance is a concept based on instances. So when... Read More

Question : What are the main differences between jdk1.4 n jdk1.5?       Answers: Jdk1.4 doesn't contain the tool interface that is JVMTI which is a profiling tool in jdk1.5.The earlier versions of java had... Read More

java bean is a reusable component,where as the servlet is the java program which extends the server capability Read More

Single Ampercent (& ) can be used as Bitwise operator and Boolean logical operator. Now the difference arises when & is used as logical operator. This can be best explained with the help of an example. int i=5; if(i<3 & i++ ... Read More

The Reader/Writer class hierarchy is character-oriented, and the InputStream/OutputStream class hierarchy is byte-oriented. Read More

ArrayList is an array that grows dynamicaly when needed. In Java an array is of fixed length. Once the array is created the user needs to know the length of the array as to operate with it since the array cannot grow nor can be reduced in size.... Read More

yes u can create executable for java just download install4j and use it Read More

Final method: Final method is a method ,which cannot be overridden in the sub classes. Read More

When you use Serializable interface, your class is serialized automatically by default. But you can override writeObject() and readObject()two methods to control more complex object serailization process. When you use Externalizable interface, you... Read More

JDBC supports both ?two tier: ( client server configuration) ?three- tier model: commands are sent to a middle tier , which then send SQL statements to the database. The database processes the SQL statements and sends the result back to the... Read More

In java, we have Sand box Security Model. Some Features Structured Memory Access(No Pointer Arithematics) Type-safe reference casting Automatic garbage collection Array bound Checking Checking references for null Read More

Question : In Java, You can create a String object as: String str = " abc"; & String str = new String("abc"); Why cant a button object be created as : Button bt = "abc" Why is it compulsory to create a button object as: Button bt = new... Read More

The == operator compares two objects to determine if they are the same object in memory. It is possible for two String objects to have the same value, but located indifferent areas of memory. Read More

ArrayList is faster than Vector, because ArrayList is not synchronized. Synchronization will reduce the performance of Vector. Read More

Java(tm) has no user-visible pointers, so how would you do a linked list? Each element needs to point to the next one, doesn't it? Well, fortunately there is a way, illustrated using this brief example: // source file link.java... Read More

The if statement is used to select among two alternatives. It uses a boolean expression todecide whichalternative should be executed. The switch statement is used to select among multiplealternatives. It usesan int expression to determine which... Read More

DeadLock. Read More

Bytecode is nothing but an optimised set of instructions designed to be executed by JVM . The JVM converts the byte code into specific machine level instructions. Yes,we can reverse engineer the code by using available tools like JAD. EXE Read More

It can be done by setting the mime type to the image filepath. For example, ServletContext sc = getServletContext(); String filename = sc.getRealPath("image.gif"); // Get the MIME type of the image String mimeType = sc.getMimeType(filename); ... Read More

Question : 1-explain singleton pattern in java 2-explain up casting and down casting 3-how do u code a singleton in java 4-How do u read XML file in java 5-gine an example of the Decorator pattern in the java API. 6-What r the... Read More

Vector class is Synchronized and ArrayList class is not Synchornized. Submitted by - Rama Krishna ( iamvemuri @ yahoo . com ) Read More

Yes, an exception can be rethrown. Read More

The Collection interface provides support for the implementation of a mathematical bag -an unordered collection of objects that may contain duplicates. Read More

The main difference: 1. Generics are introduced in jdk1.5 2. The concept of Out-boxing and boxing is introduced. Read More

The 'main()' method in Java is referred to the thread that is running, whenever a Java program runs. It calls the main thread because it is the first thread that starts running when a program begins. Other threads can be spawned from this... Read More

Serialization is the process of writing the state of an object to a byte stream. Deserialization is the process of restoring these objects. Read More

Hash table based implementation of the Map interface. This implementation provides all of the optional map operations, and permits null values and the null key. (The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized... Read More

A transient variable is not stored as part of its objects persistent state. A transient variable is not stored with its Object; therefore, it is not serialized when the method writeObject( ) is invoked. Submitted by Amit Mathur _________ ... Read More

If a thread attempts to execute a synchronized method or synchronized statement and is unable to acquire an object's lock, it enters the waiting state until the lock becomes available. Read More

The Object class is extended by all other classes. Read More

When a task invokes its yield() method, it returns to the ready state. When a task invokesits sleep()method, it returns to the waiting state. Read More

The synchronized keyword tells the JVM that the method requires a lock in order to run. The JVM then creates the lock and manages the allocation of the lock to threads during execution. When a thread has the lock for a class, it is the only thread... Read More

Yes, a double value can be cast to a byte. Read More

When a task's interrupt() method is executed, the task enters the ready state. The next time the task enters the running state, an InterruptedException is thrown. Read More

Middleware: Software that facilitates interoperability by mediating between an application program and a network, thus masking differences or incompatibilities in network transport protocols, hardware architecture, operating systems, database... Read More

A static variable is one that is not removed from memory after creation, even when it goes out of scope. The concept is very similar to that of a global variable, except that while a global variable is accessible from anywhere, a static variable is... Read More

No, an object cannot be cast to a primitive value Read More

The Frame class extends Window to define a main application window that can have a menu bar. Read More

A transient variable is a variable that may not be serialized. If you don't want some field not to be serialized, you can mark that field transient or static. Read More

A Set is a collection that has no duplicate elements. A List is a collection that has an order assoicated with its elements. A map is a way of storing key/value pairs. The way of storing a Map is similar to two-column table. Read More

Virtual methods are used to use the polymorhism feature in C++. Say class A is inherited from class B. If we declare say fuction f() as virtual in class B and override the same function in class A then at runtime appropriate method of the class will... Read More

Yes, a for statement can loop indefinitely. For example, consider the following:for(;;) ; Read More

Java does not support typedefs, defines, or a preprocessor. Without a preprocessor, there are no provisions for including header files. Since Java does not have a preprocessor there is no concept of #define macros or manifest constants. However,... Read More

Serialization is the process of converting a set of object instances that contain references to each other into a linear stream of bytes, which can then be sent through a socket, stored to a file, or simply manipulated as a stream of data.... Read More

The JNI is used to write native methods to handle situations when an application cannot be written entirely in the Java programming language such as when the standard Java class library does not support the platform - dependent features or... Read More

The Vector class provides the capability to implement a growable array of objects. Read More

Type casting is used to convert the one data type into another data type.for example lower data type into higher data type vice versa lower to higher means widening higher to lower means narrowing Read More

The read() method returns -1 when it has reached the end of a file. Read More

A private variable may only be accessed within the class in which it is declared. Read More

Without layout managers, Java programmers are faced with determining how their GUI will be displayed across multiple windowing systems and finding a common sizing and positioning that will work within the constraints imposed by each windowing... Read More

When an exception is thrown within the body of a try statement, the catch clauses of thetry statement areexamined in the order in which they appear. The first catch clause that is capable ofhandling the exceptionis executed. The remaining catch... Read More

If any object variable is still pointing to some object which is of no use, then JVM will not garbage collect that object and object will remain in memory creating memory leak Read More

The JDBC is a pure Java API used to execute SQL statements. It provides a set of classes and interfaces that can be used by developers to write database applications. The steps needed to execute a SQL query using JDBC: 1. Open a connection to... Read More

The Util package bascially contains Collection as its part. A collections framework is a unified architecture for representing and manipulating collections. All collections frameworks contain the following: Interfaces: These are abstract data types... Read More

A. List are collections where 1. Elements are stored in a particular Order 2. Repetitions of elements are allowed B. Sets are collection where 1. Elements are stored in any order (just like pebbles put in a pocket) 2. Repetitions are... Read More

 Map (in the API reference documentation) is an object that maps keys to values. A map cannot contain duplicate keys: Each key can map to at most one value. The Map interface follows. public interface Map { //Basic operations V put(K key, V... Read More

Abstract method: It is a method we are unable to provide implementation to that method at the time of writing that method. We will provide implementation to that method in the derived class. eg: paint () is a abstract method,service() ,doGet()... Read More

There are two methods in the Externalizable interface. You have to implement these two methods in order to make your class externalizable. These two methods are readExternal() and writeExternal(). Read More

A non-static inner class may have object instances that are associated with instances ofthe class's outer class. A static inner class does not have any object instances. Read More

The SimpleTimeZone class provides support for a Gregorian calendar. Read More

Garbage collector: Whenever an object is no longer used in the program,Java reclaims the memory of that an object.It is performed by the Java implicitly,no need to care of it.Finalize() will be called before sweeps the memory of an object by java... Read More

Throw is used to throw an exception manually, where as throws is used in the case of checked exceptions, to reintimate the compiler that we have handled the exception. so throws is to be used at the time of defining a method and also at the time of... Read More

Under preemptive scheduling, the highest priority task executes until it enters the waitingor dead states ora higher priority task comes into existence. Under time slicing, a task executes for apredefined slice oftime and then reenters the pool of... Read More

When a thread terminates its processing, it enters the dead state. Read More

Use of Interface: Java doesnot support multiple inheritance directly.So java is not pure oop.Using interfaces java supports multiple inheritance.By using using interfaces code is very easy and simple. _________________ Submitted by Devarathnam... Read More

The order of invocation of Applet is as follows: 1.init() 2.start(); 3.stop(); 4.destroy(); Submitted by Chinnakotla Devarathnam (devarathnam@yahoo.co.in) Read More

The setLayout() method is used to specify a container's layout. Read More

Without layout managers, Java programmers are faced with determining how their GUIwill be displayedacross multiple windowing systems and finding a common sizing and positioning thatwill work within theconstraints imposed by each windowing system. ... Read More

Method declaration is a java Statement which contains returntype and method name and arguments in it are optional and ends with a semicolon. Method modifiers are the access modifiers. Read More

There is no method in the Serializable interface. The Serializable interface acts as a marker, telling the object serialization tools that your class is serializable. Read More

The Object class is the highest-level class in the Java class hierarchy. The Class class is used to represent the classes and interfaces that are loaded by a Java program. Read More

Java does not support multiple inheritance directly.Because to avoid the Ambiguty among the classes.But java support multiple inheritance in different way i.e. INTERFACES. Submitted by Chinnakotla Devarathnam (devarathnam@yahoo.co.in) Read More

The vector container class generalizes the concept of an ordinary C array. Like an array, a vector is an indexed data structure, with index values that range from 0 to one less than the number of elements contained in the structure. Also like an... Read More

equals method compares content of the two objects where as "==" does object reference copmparsion Read More

Final variable: Final variable is a variable ,you can't modify it.It is just like "const" variable int c/c++.Final variable must initialialized other wise it leads to compile errors.Final variable can't inherited into derived class. eg:... Read More

A Java source code file takes the name of a public class or interface that is defined within the file. A source code file may contain at most one public class or interface. If a public class or interface is defined within a source code file, then... Read More

Window. Read More

How fast objects are created does not affect when they are garbage collected. When the object is dereferenced it becomes available for garbage collection. If the only references to an object are from other objects that themselves are candidates for... Read More

This is used to refer to the current object instance. super is used to refer to the variablesand methods of thesuperclass of the current object instance. Read More

Difference b/w Swing and Applet: Swing : 1.swing is a peer based cmponent 2.swing components are lightly dependent on underlaying os. 3.swing components will be appear any os unique. 4.to design swing components is very easy. 4.which are... Read More

The wrapper classes are under the java.lang and java.util directories. The wrapper classes are: Double, Integer, Character, and Boolean. Wrapper classes are final and hence cannot be sub classed.. The methods of the wrapper classes are all... Read More

An object reference be cast to an interface reference when the object implements the referenced interface. Read More

String string = "aString"; // First occurrence. int index = string.indexOf('S'); // 1 // Last occurrence. index = string.lastIndexOf('i'); // 4 // Not found. index = string.lastIndexOf('z'); // -1 Read More

The elements of a BorderLayout are organized at the borders (North, South, East, andWest) and the center of a container. Read More

An object's lock is a mechanism that is used by multiple threads to obtain synchronized access to the object. A thread may execute a synchronized method of an object only after it has acquired the object's lock. All objects and classes... Read More

this() is used to invoke a constructor of the same class. super() is used to invoke a superclass constructor. Read More

The Serializable interface is just a "marker" interface, with no methods of its own to implement. Read More

The window, Frame and Dialog classes use a border layout as their default layout. Read More

Applet Communication:By using AppletContext() we can communicate in two applets. _______________________ Submitted by Devarathnam.C, S.V.University, Tirupati (devarathnam@yahoo.co.in) Read More

The Set interface provides methods for accessing the elements of a finite mathematicalset. Sets do notallow duplicate elements. Read More

Enumeration and Iterator both are interfaces present in util package. Enumeration is a legacy interface which does not come under the collection framework, wheras Iterator is an interface present in the collection framework. All the legacy classes... Read More

It is referred to as the modulo or remainder operator. It returns the remainder of dividing the first operand by the second operand. Read More

JAR is useful to run setup prog.to install java application on operating system its seems like exe file in windows. Read More

There are four drivers in JDBC. 1.JDBC-ODBC BRIDGE. 2.PARTLY JAVA DRIVER. 3.INTERMEDIATE DATABASE DRIVER(Network purpose). 4.PURE JAVA DRIVER. Submitted by Chinnakotla Devarathnam (devarathnam@yahoo.co.in) Read More

In Java Object are passed by reference and Primitive data is always pass by value Read More

By using the static method there is no need creating an object of that class to use that method. We can directly call that method on that class. For example, say class A has static function f(), then we can call f() function as A.f(). There is no... Read More

RMI: Remote Method Invocation(RMI) is a technology.RMI allows you to invoke the methods in the two different JVM s, which is platform independent and language dependent. _________________ Submitted by Devarathnam.C, S.V.University, Tirupati ... Read More

one JVM will be consired, since JVM is consider as the JavaByte code interpreter(not specfic to any system o any processor), that will consider the javaprogram and convert in to the Native system call. Read More

Creates and returns a copy of this object. The precise meaning of "copy" may depend on the class of the object. The general intent is that, for any object x, the expression: x.clone() != x will be true, and that the expression: x.clone().getClass() =... Read More

Threads block on i/o (that is enters the waiting state) so that other threads may execute while the i/o Operation is performed. Read More

run this file, i think result will itself explain you the use of LOG4J. otherwise mail me ritesh.patni@ gmail.com :- package com.banking.log4j; import org. apache.log4j.*; import com.lnt.banking.constant.ConstantIf; public class... Read More

Light weight component:Swing is a lightweight component.which are lightly dependent on the underlaying domain. Submitted by Chinnakotla Devarathnam (devarathnam@yahoo.co.in) Read More

You may synchronize a class, a method or a portion of a method. Synchronization will make the code thread safe. Read More

Classes which implements different collection interface are:-- HashSet,TreeSet(For Set interface) ArrayList,LinkedList,Vector(for List interface). HashMap,TreeMap (for Map interface). Read More

MVC is an approach for developing interactive applications ie it results in events through user interaction.MVC stands for Model View Controller.Model is responsible for holding the application state,view is for displaying the current model and... Read More

The only statements for which it makes sense to use a label are those statements that canenclose a break orcontinue statement. Read More

 Framework which provides classes and interfaces for holding a group of objects. ? Like Arrays but has more features in terms of flexibility and maintainabiliy ? Consistent, well-defined API for maintaining groups of objects in containers ? A... Read More

Consider the following bean: package bar; public class FooBean { public FooBean(SomeObj arg) { ... } //getters and setters here } The only way you can instantiate this bean within your JSP page is to use a scriptlet. For example, the... Read More

Access specifiers are public,private,protected,default were access modifiers are static,final,abstact,transient,synchronized and volitale Read More

The first statement of the constructor should be either a call to super() or this(). ex. class A{ A(){ super(); / this(); } } Read More

Object is the root class for all java classes. Submitted by Chinnakotla Devarathnam (devarathnam@yahoo.co.in) Read More

True Read More

Question : I need some more information about interface. For Example there is no any functionality inside the method which is declared in any interface. Then why i want to implement that interface to my class. 2. Statement is an interface.... Read More

A native method is a method that is implemented in a language other than Java Read More

Hashmap can contains null values as the keys and as well as values.But Hashtable dose not allow null values as keys and values. hashtable is syncroniged.hashmap is not syncroniged.hashtable can change the iterator. Read More

Process is a program in execution whereas Thread is a separate path of execution. Read More

servlet is serverside programming.when client send request to sever then by using servlet server try to response to client. Read More

The JDK 1.02 event model uses an event inheritance or bubbling approach. In this model, components are required to handle their own events. If they do not handle a particular event, the event is inherited by (orbubbled up to) the component's... Read More

Final keyword is used for define constant variables and method and no body can change that variable and method within program. Read More

The garbage collector invokes an object's finalize() method when it detects that the object has become unreachable. Read More

Vector implements a dynamic array at run tme and it works as arraylsi,but it is synchronizedand not part of the collection framework Read More

Difference b/w Applet and Application: Applet : 1.Applet is a small java program,which is executed in the special browser. 2.Applet should not contain main () method. 3.Applet travel in the internet. Application: 1. Application is... Read More

An event-listener interface defines the methods that must be implemented by an event handler for aparticular kind of event. An event adapter provides a default implementation of an event listener interface. Read More

In servlets, session can be tracked using a) URL rewriting b) Hiddin FormField c) cookies and d) HttpSession API In EJB to maintain session go for stateful session beans. Read More

final" is a modifier in java.You can use "final" key word for classes, methods and variables. "finally" ,it is a block in exception handling, whatever u write in that block that would be executed 100% irrespective of the exception. "finalize()" This... Read More

In the context of "exception handling" "try", "catch", "finally", "thow" and" throws" plays an anologous role in the java programming language. "try": This block will throw an exception. "catch": This block will catch an exception that is raised in... Read More

Applet life cycle: An Applet is a small java program,which is executed in the special browser(like appletviewer) the lifecycle of an applet is as follows: 1.init(); 2.start(); 3,stop(); 4.destroy(); The init(),and destroy() methods... Read More

string x="abc" string y ="abc" i dont think that here they refer to same object.I have refer the complete reference..automatically when u asign stringz like this ..different objects will b created Read More

No.String class cannot be extened as it is final class. Read More

An anonymous class is a local class that has no name.. An anonymous class is never abstract. An anonymous class is always an inner class; it is never static. An anonymous class is always implicitly final. Read More

static class means the class which has all static methods in it.This makes us not to create the object to call the methods in it.we can directly call the methods in it by using ClassName.methodName() Read More

Question : What is the difference between Applet and japplet? What are the traverses in binary tree? Write down how will you create a Binary tree? What is constructor and virtual function? Can we call a virtual function in a constructor?... Read More

Constructing a String If you are constructing a string with several appends, it may be more efficient to construct it using a StringBuffer and then convert it to an immutable String object. StringBuffer buf = new StringBuffer("Initial Text"); // ... Read More

The painting algorithm takes as input a source image and a list of brush sizes. sweep algo is that it computes the arrangement of n lines in the plane ... a correct algorithm, Read More

The Dictionary class provides the capability to store key-value pairs. Read More

The start() method of the Thread class is invoked to cause an object to begin executing as a separate thread. Read More

Synchronized methods are methods that are used to control access to an object. A thread only executes a synchronized method after it has acquired the lock for the method's object or class. Synchronized statements are similar to synchronized... Read More

The ResourceBundle class is used to store locale-specific resources that can be loaded by a program to tailor the program's appearance to the particular locale in which it is being run. Read More

Class ABC { static final float GRAVITATIONAL_CONSTANT = 9.8; public void getConstant() { system.out.println("Gravitational_Constant: " + GRAVITATIONAL_CONSTANT); } } Read More

import java.io.*; class FileOutputDemo { public static void main( String args[]) { FileOutputStream out; // declare a file output object PrintStream p; // declare a print stream object try { // Create a new file output stream //... Read More

public String toString(); public Object clone(); public boolean equals(); public int hashCode(); Read More

validate(). Read More

You can not access the private method of a class by reflection. Read More

A synchronized block is a thread safe block which means it cant be accessed by more than one object at a time. It is accessed by objects in a queue on a priority basis.So it can be used to make data integrity. While a normal block can be accessed... Read More

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Simply speaking a class or a method qualified with "abstract" keyword is an abstract class or abstract method. You create an abstract class when you want to manipulate a set of classes through a common interface. All derived-class methods that match... Read More

The Java runtime environment deletes objects when it determines that they are no longer being used. This process is known as garbage collection. The Java runtime environment supports a garbage collector that periodically frees the memory used by... Read More

Volatile modifier applies to variables only and it tells the compiler that the variable modified by volatile can be changed unexpectedly by other parts of the program. Read More

We can do by the reflection mechanism. For example here is the code. TestConstructor testConstructor; // This is my class which i want to call. For arguments of construtor. Class[] args = new Class[] {String.class} // specify the type of... Read More

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If you have the better answer, then send it to us. We will display your answer after the approval. Read More

Question : write classes/methods to calculate the total length of a set of lines given the start and end points taking into account overlapping. E.g. Line 1 start: -1.4, end: 3.2 Line 2 start: 2.9, end: 4.1 etc.. Total... Read More

Question : what will this print int i=10000 System.out.println(i*i); and explain why ? Answers: If we write program as...class First{public static void main(String s[]){ int i=10000System.out.println(i*i);}}It will... Read More

Reflection (introspection) is querying a class about its properties, and operating on methods and fields by the name for a given object instance. Reflection is possible in the Java language because of late binding. Read More

We use tagged interface to indicate compiler or runtime to do some activity in our behalf like we use serializable interface to indicate that a particular class can be serialized. Read More

Question : what happens if i do this=null? 2)how to swap 2 variables without using third temp variable in java? 3)constructors can not be inherited,why     Answers: 1.It shows compile time error when we make this=null i.e... Read More

First of all class doesnot support multiple inheritance consider class A as superclass class B and C are sub class of A.comment : class cannot extend more than one class think class D extends B and cthe method present in class A,B,C are alike if u... Read More

The String literal "abc" is not a primitive value. It is a String object. Read More

The initial size of the hash table is 11. and the load factor is 0.75.if it reach the bound(i.e. 11*0.75=8) then its doubled the size ie 16. like that it keep on increase its size up to RAM size Read More

The serialization is a kind of mechanism that makes a class or a bean persistence by having its properties or fields and state information saved and restored to and from storage. Read More

The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected. Read More

The finally clause of the try-catch-finally statement is always executed unless the thread of execution terminates or an exception occurs within the execution of the finally clause. Read More

1. Applets can be embedded in HTML pages and downloaded over the Internet whereas Applications have no special support in HTML for embedding or downloading. 2. Applets can only be executed inside a java compatible container, such as a browser or... Read More

you can declare a static method(member method) inside which you can use System.loadLibrary(String LibraryName).The code below might help you(though i have not used it). code: public class xxxx { static void loadLib() { System... Read More

using system.gc() method Read More

There are two types of casting, casting between primitive numeric types and casting between objectreferences. Casting between numeric types is used to convert larger values, such asdouble values, tosmaller values, such as byte values. Casting between... Read More

Log4j is the property file where you can assign the current application mode in"DEBUG", "INFO", "ERROR", "WARN" etc.sO at the time of running the application you can see "DEBUG" , "ERROR", etc. related messages in Tomcat Webserver. Read More

The paint() method supports painting via a Graphics object. The repaint() method is usedto cause paint() tobe invoked by the AWT painting thread. paint() method can only be called only once in a program directly.. repaint() method can be... Read More

The "public" keyword is an access specifier,which allows the programmer to control the visibility of class members. When a class member is preceded by "public",then that member may be accessed by code outside the class in which it is declared. In... Read More

Teh persn u ask.evr1 has different idea. msot aggree taht " scripting languages" are "compiled" real time, while " programming lagnuages" are compiled ahed of time.But it is not alwas tht clear cut. U can get a C "scrpting engine", or u cn get a... Read More

You can stop (kill) a thread by calling the method 'stop()' on the thread object. But it is not preferable to kill a thread, because it may cause system failure when writing to important data structures. Read More

You cannot make a constructor as STATIC, because if you use any access modifier in constructor compiler interprets it to be a method and expects a return type this class will not compile until you specify a return type, since compiler thinks it to... Read More

A class does not inherit constructors from any of its superclasses. Read More

The operating system's task scheduler allocates execution time to multiple tasks. By quickly switching between executing tasks, it creates the impression that tasks execute sequentially. Read More

There is no such thing as a "Boolean &" operator. The & operator is the bitwise-AND operator, and combines two values. It's often used for masking off part of a variable (e.g., to get the two low-order bytes of a 32-bit value, use the... Read More

It is very simple. Get the data that has to be passed from one thread. Set the data in a global variable. now get the data from the glo bal variable !! It is one of the easiest questions i have ever heard ! Read More

.PREORDER (root-left-right) 2.INORDER (left-root-right) 3.POSTORDER. (left-right-root) and converse of above. Submitted by Chinnakotla Devarathnam (devarathnam@yahoo.co.in) Read More

Polymorphism:The ability to take more than one form. eg: int area(int a,int b); int area(int a,int b,int c); Here function "area()"is same but it will performs different tasks depending on passing different arguments. Submitted by... Read More

Object serialization is the process of saving an object's state to a sequence of bytes, as well as the process of rebuilding those bytes into a live object at some future time. To persist an object in Java, we must have a persistent object.... Read More

Features:-===========================================<font face=verdana size=10><center><TABLE border=0 cellPadding=0 cellSpacing=0 width="70%"><TR><TD><STRONG>Topic</STRONG></TD><TD><STRONG>... Read More

When we r implementing the some comman methods in the every class at that time we keep that all methods in the one interface. Another way example:- for example for CD Writer soft ware dovelepment all companies(LG,SAMSUNG) follow the method names r... Read More

Try statements may be tested. Read More

Integer / and % can result in the throwing of an ArithmeticException. Read More

The purpose of garbage collection is to identify and discard objects that are no longerneeded by a programso that their resources may be reclaimed and reused. Read More

JFC stands for Java Foundation Classes. It is more like an extension to the API's which was available in JAVA. It was implemented and released in 1998 ( im not very sure abt the date though ) In simpler terms it consists of the API'... Read More

"==" is called the "Object Reference Equality" & "equals()" method is called the "Object Value equality". Object1 == Object2; In above == checks if both reference variables, Object1 & Object2 refers to the same object. If it does... Read More

yes.This is the correct answer. Read More

So they can be invoked as if they are a mathematical code library. Read More

java -version command will return the installed java version. Read More

Skeleton is class created by RMI. Read More

Unicode requires 16 bits and ASCII require 7 bits. Although the ASCII character set usesonly 7 bits, it is usually represented as 8 bits. UTF-8 represents characters using 8, 16,and 18 bit patterns. UTF-16 uses 16-bit and larger bit patterns. Read More

public class readAFile{ public static void main(String args[]) { try{ FileInputStream fis = new FileInputStream("Input.txt"); int i = 0; do{ i = fis.read(); if(!=-1){ System.out. print((char)i); } }while(i!=-1); }catch(Exception ex){ ... Read More

Functions which are called at runtime are known as virtual functions. Virtual functions are used to encorporate runtime polymorphism or in other words dynamic binding. Read More

A class with in the class is called innerclass.it is a safety mechanisam.innerclass variables are accessed througth outerclass variables only. anonymous class is an innerclass whose class name will be hidden .whom will be created only object. Read More

As any Java programmer knows, you can?t put an int (or other primitive value) into a collection. Collections can only hold object references, so you have to box primitive values into the appropriate wrapper class (which is Integer in the case of... Read More

ArrayList will grow half the size what you initialise ..where as vector will grow doble the initial size.. Read More

The purpose of the System class is to provide access to system resources. Read More

Some times, If the variable is global for a packege. Read More

Create a wrapper class Integer of int. Now u can pass the Integer class by reference. Read More

Multitasking is running several processes at a time. Multi threading runs several threads of a single process at a time.The priority levels of threads are from 1-10.Normal priority comes to 5. Multi threading is normal in any window environment,... Read More

An object's finalize() method cannot be invoked by the garbage collector while the objectis still reachable.However, an object's finalize() method may be invoked by other objects. Read More

Every thread occoupy a seprate copy I because it initialize when satrt method is call. Read More

The List interface provides support for ordered collections of objects. Read More

getLabel() and setLabel(). Read More

An abstract class may not be declared as final. Read More

A particular class has to implement an Interface java.io.Serializable for implementing serialization. Read More

There 4 drivers available in java they are JDBC-ODBC bridge driver Native API partly java driver JDBC Net pure java driver Native protocol pure java driver Read More

A void return type indicates that a method does not return a value. Read More

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Prepared statement is a precomplie SQL statement.It is the compiled version of the query.Prepared statement has got a faster excecution time than any other statement Read More

1. Difference between Enumeration and Iterator interface is Enumeration has two methods hasMoreElements() and nextElement() and Iterator has three methods hasNext() and next() and remove(). 2. Whatever we can achieve with Enumeration we can... Read More

The interface supports multiple Inheritance .with one reference we can call all methds of interface witch was implemented in all classes. Read More

E is the base of the natural logarithm and PI is mathematical value pi. Read More

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The addpter pattern converts the interface of a class into another interface the client expect. Adapter lets classes work together that could't otherwise because of incompatible interface Read More

Thanks in advance.i want to move a JButton using Mouse in runtime within a JFrame.saran Read More

A throw statement may throw any expression that may be assigned to the Throwabletype. Read More

Internationalization is the process of designing an application so that it can be adapted to various languages and regions without engineering changes. Sometimes the term internationalization is abbreviated as i18n, because there are 18 letters... Read More

i dont think it is directly possible thru any methods. u can use a static avriable to achive this. go thru following code: public class test1 { static int cntr=0; test1() { cntr++; if(cntr>2) throw new NullPointerException();//u can define a new... Read More

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 abstract method are the methods that have no implementation of its self(i.e by superclass).they do not have body.so the subclass have to override them . Read More

An I/O filter is an object that reads from one stream and writes to another, usually altering the data in someway as it is passed from one stream to another. Read More

Thread can be used in two ways 1.By implementing Runnable interface 2.By Extends Thread class Read More

The elements of a Grid layout are of equal size and are laid out using the squares of a grid. Read More

The left operand is an object reference or null value and the right operand is a class,interface, or array type. Read More

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Taking a big step back, a Web server serves pages for viewing in a Web browser, while an application server provides methods that client applications can call. A little more precisely, you can say that: A Web server exclusively handles HTTP... Read More

C and c++ methods can be used as native methods,but you need to load the class before that as a library! Read More

An executing thread is in the running state. Read More

jdbc is a java database connectivtiy is given by sun microsystemdriver the code is: import java.sql.*; Class.forName("sun.jdbc. odbc.JdbcOdbcDriver"); Connection cn=DriverManager.getConnection("domain name: subdomain:db name"); Read More

JDBC: Java DataBase connectivity. By using the JDBC-ODBC driver we can connect to the database Read More

An interface is a specification that exists between software components that specifies a selected means of interaction, by means of properties of other software modules, which abstract and encapsulate their data. Java does not support multiple... Read More

getState(). Read More

They handle web requests, returning data or HTML programmatically rather than from a static file. They can access databases, perform calculations, and communicate with other components such as Enterprise JavaBeans. Read More

Pure Object Oriented is that use principally the terms like: encapsulation, polymorphism, dynamic-binding.If you think Object Oriented means then can understand what these terms means.I'll tell you only that java can "extends" and "implements"... Read More

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The == operator compares two objects to determine if they are the same object inmemory. It is possible for two String objects to have the same value, but located in different areas of memory. Read More

RMI, Remote Method Invocation is an alternate to RPC, used to invoke the methods (often called as Services) provided by an object of One JVM in another JVM. This is the Remoting Technology that is supported by Java. This technology can be... Read More

If you have set up your path correctly, you can type the following at the command prompt: java -version Read More

Both apply OOPS. but Java adopts byte code conversion whereas c++ does not. c++ supports destructors whereas Java doesn't support. c++ uses pointers but Java doesn't.....so more secure.... Multiple inheritance can be possible in c+... Read More

Abstract classes are designed with implemantion gaps for sub-class to fill in. interfaces are sintacticlly similar to classes but they lack insance variables & methods. abstract classes can also have both abstract methods & non-abstract... Read More

A method's throws clause must declare any checked exceptions that are not caught within the body of the method. Read More

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java.lang.object Read More

AWT is the AbstractWindowToolkit.AWT is the heavy weight component,why Because It hides the peers component to the user.in AWT 2 instances are created,it hides to user.where as swings are the light weight component.it wont create peers component. Read More

The ObjectInputStream class supports the reading of objects from input streams. Read More

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Overloading: The same method name with a different signature (generally input argument list) written in the same class. Overriding: The identical method signature from a parent (super) class written in a subclass and modification of the method... Read More

The Java runtime system generates RuntimeException and Error exceptions. Read More

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Get the frames contentpane and add the panel frame.getContentpane().add(panel); Read More

A Choice is displayed in a compact form that requires you to pull it down to see the listof availablechoices. Only one item may be selected from a Choice. A List may be displayed in such away that severalList items are visible. A List supports the... Read More

For ur answer refer to text books, my question here, are session thread safe??, also execute method of the action class is thread safe??, i mean can multiple request process with in the execute method Read More

A program's main() method has a void return type. Read More

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Abstract Class:- it has abstract methods and non-abstract methods. Abstract Methods:- this methods has no body. these final and variables of these methods are static, final and protected. Read More

I didn't understand ur question properly. My understanding is by expand you mean extend. If I am right, you can extend interfaces in java. It's same as extending classes in Java. Read More

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In java first edition there is no multiple inheritance,but later editions they provided indirect multiple inheritance by interfaces and extends. Read More

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To wakes up the threads which are in waiting stateaddition notes:-notify() wakes up a single thread which is waiting on the object's lock notifyAll() wakes up ALL waiting threads; the scheduler decides which one will run they can only be used... Read More

We can use access specifier's and we can overload the methods also. but we can't override methods( by changing only access specifier is just like a override.) Read More

Anonymous classes are classes that don?t have a name (hence the term anonymous). Because they don?t have a name, there is no way to refer to them. For this reason, their declaration must be given at creation time, as part of the new statement.That... Read More

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The non-Unicode letter characters $ and _ may appear as the first character of an identifier. Read More

Class is a programme means set of instructions and method is part of that class whichever is available in. That's why classes and methods are not garbage collected. but it's instance is garbage collected. Read More

Static keyword ,means only one copy per class if u have a static block or static method it will run first then only other statements like constructor will run . it dosen't need an object to access its method .Though u can access it using object... Read More

By associating Checkbox objects with a CheckboxGroup. Read More

Immutable means unchangeable i.e. U cannot change the content and length of String object. But StringBuffer object is Mutable. i. e. u can change length, content etc.. Let me explain with an example, ??? String s1=new String("Senthil"); ???... Read More

Transiate is a access modifier that can not be serialized, Means it is unable to maintain its state.If we declare any varrible as transiate then that varrible is cannot be serialized.We cannot send that data onto the network. Read More

A protected method may only be accessed by classes or interfaces of the same package orby subclasses ofthe class in which it is declared. Read More

compile time polymorpism also known as staic poly run time polymorpism also known as dynamic polymorpism example for static poly is method overloading example for dynamic poly is method overriding static poly is linking method call at the time of... Read More

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Polymorphism:Behaving differentely at the different placess.Ability to take more than one form.Inhetitance:Aquring the parent properties into child properties.Creating the new class from alredy exiting class.Encapsulation:Wrapping of the methods &... Read More

The compiler supplies a default constructor for a class if no other constructors are provided. Read More

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If we want to implement all the methods in a child class then w e will go for Interface and if we want to implement a few methods , if we want to use a few methods of its super class we go for Abstract class. Read More

Through Internationalization Read More

Synchronization hits panelty on performance so when you want to only some portion of you method code synchoronized in that case use synchronized statement in you method. Otherwise if you wish whole your method synchronized use synchronized method. Read More

1> Implementing Runnable interface. 2>Extending Thread class. First case we have to override run method of the interface. Read More

vector -10stringBuffer-50 Read More

Class C extends A implements B { } Read More

Java is platform independent but it uses an respective jvms for each platform .Net is also platform independent ie., it works on more than one os but the thing is that those platforms alll belong to windows. The thing that microsoft havent... Read More

The standard input, output, and error streams -- System.in, System.out, and System.err -- are all byte streams. You can use System.err.print and System.err.println to write to standard error on to the console. Read More

The File class is used to create objects that provide access to the files and directories of alocal file system. Read More

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wait() and notify() both extend from object class. wait() -- causes current thread to wait until another thread invokes the notify() or notifyAll() method for this object. notify() -- wakes up a single thread that is waiting on this object'... Read More

One can delcare a private constructor for maintining the object creation ... maybe it just wants the object to be created once .... or maybe using a static method such as getInstance() one can give access to constructor which is private....Basically... Read More

Difference b/w Static and Non-static variable: Static variable is a variable ,which is not repeated to each and every object .It is shared by all objects .It is also known as Class variable.Static methods only access the static variable.By default... Read More

Java Bean is a class which is used to build reusable components.It has no main method.Moreover, it is mainly developed for building GUI components. The variables and methods declared inside the bean class are referred as property. Read More

An object must implement the Serializable or Externalizable interface before it can be written to a stream as an object. Read More

High severity means a matching high priority, take the example of a bugzilla with a high severity and a low priority. For example, if the defect is a problem that blocks use of a enhancement, but that enhancement is a corner case that has few (if any... Read More

No answer available currently. Be the first one to reply to this question by submitting your answer from the form below.   Read More

Exception itself is a defined class without any super class. Read More

A local inner class may be final or abstract. Read More

Question : What is the difference between importing a class and creating the object for that class Answers: If there is any class another then in java.lang package(which get imported by default) then we need to import that... Read More

<input type=file name=f> Read More

The Collection interface provides support for the implementation of a mathematical bag -an unorderedcollection of objects that may contain duplicates. Read More

Question : If we are having Interface A,Interface B,Interface C and Class D where A,B,C are Base classes and D has extended the features of all the three if A,B,C are having totally 5 methods and D has developed only 3 of them what will happen... Read More

Design Pattern meansit states about rules and regulations to be followed while implementing some s/w, whereas architecture states how a particular s/w is to be implemented. Design pattern concentrates on how Architecture concentrates on what Read More

Swings are light wait components than AWT components. Swings are OS independent, having more component in swings than in AWT. Read More

Question : My quetion is about the protected class. it have one super and sub class example , below example i read from one pdf. package certification; public class Parent { protected int x = 9; // protected access } -------------... Read More

Java has only pass by value associated with it. Even when an Object is passed the value of Object reference in the Stack is passed(not the actual Object in Heap) But since the value passed in is a reference to an Object any modification to the... Read More

The elements of a GridBagLayout are organized according to a grid. However, the elements are of differentsizes and may occupy more than one row or column of the grid. In addition, the rows andcolumns mayhave different sizes. Read More

It will not compile because there is no java virtual machine.even though it is executable jar file it need java virtual machine. Read More

Overridden methods must have the same name, argument list, and return type. The overriding method may not limit the access of the method it overrides. The overriding method may not throw any exceptions that may not be thrown by the overridden method. Read More

Yes, by using System.gc we can implicitly call the garbage collector Read More

A component can handle its own events by implementing the required event-listener interface and addingitself as its own event listener. Read More

Final static Read More

Firstly convert the string into a list of characters and after that compare each character with its precedence(like checking with the character) Read More

The ActionEvent event is generated as the result of the clicking of a button. Read More

I think we can have two different applications with same name.we can differnciate diffenrent applications by their application names but not with port number.so we can have same port numbers Read More

By using int getServerPort of ServletRequest Interface Read More

We can use clone() method to create another instance of a singleton class. Example: SingletonObjectClass obj = SingletonObjectClass.createSingletonObject(); SingletonObjectClass clone = (SingletonObjectClass) obj.clone(); java.lang... Read More

An interface may be declared as public or abstract. Read More

Difference b/w the Classpath and Import: Classpath: Class path is a system variable. It is a collection of files in the directories.Normally classpath will be used by Java interpreter to exucute the class files(.class). Import :Import is a... Read More

The array list always stores objects, but int is primitive data type, its not object. If you stiil want to store int in arraylist, then you transform [wrap] it in Integer Object and then store it in arraylist. Read More

During compilation, the values of each case of a switch statement must evaluate to avalue that can bepromoted to an int value. Read More

EventAdapter classes are implicitly provide the default implementation of all EventListener interfaces.Using these event dapter classes you can implement required methods ,rest of methods you may ignore. Submitted by Devarathnam.C (devarathnam... Read More

If a class is marked final it means that the reference to this class cannot be changed and the methods marked final mean that they cannot be overridden Read More

By using BufferedReader we access parameter as String and by type-casting into it into (Integer.parseInt(variable_name)) int, float, char, double, long etc. U don't get parameter as primitive type use Wrapper classes Read More

If you have the better answer, then send it to us. We will display your answer after the approval. Read More

If u wanna class that should not be extened we can use final class.no is not draw back of oo but is nothing but encapsulation that is going to hide information. Read More

No. when there is user-defined parametrized constructor, then the compiler will not make a no-arg. constructor. Read More

Synchronisation work with locks. o There is one built-in lock per each java object o If one thread picks up the lock, no other thread can enter the synchronised code. o A method or a code block could be synchonized Read More

Constructing a String If you are constructing a string with several appends, it may be more efficient to construct it using a StringBuffer and then convert it to an immutable String object. StringBuffer buf = new StringBuffer("Initial Text"); // ... Read More

Question : I need your help to answer the code shown below. using System; using System.Collections.Generic; using System.Text; using System.Collections; namespace ApplicantTestin { /// The DataObject class stored with a key ... Read More

String : String is a immutable class.You can't modify it. StringBuffer: StringBuffer is a mutable class .You can modify it. Submitted by Devarathnam.C (devarathnam@yahoo.co.in) Read More

No.This is No.This is the correct answer. the correct answer. Read More

String string = "aString"; // First occurrence. int index = string.indexOf('S'); // 1 // Last occurrence. index = string.lastIndexOf('i'); // 4 // Not found. index = string.lastIndexOf('z'); // -1 Read More

This=null assigns null value to the current invoking object Read More

The eight primitive types are byte, char, short, int, long, float, double, and boolean. Read More

Import statement doesn't make your class bigger. Why because, importing a class means that to tell the compiler to load the specified class into memory during compilation. If you specify more classes in import statements, your class will take... Read More

No, it is not. Read More

Integer.parseInt() method throws a NumberFormatException if any data other than the number (within the range of java ?int? data type) is passed as argument, even when we pass spelled-out numbers, like "three". Read More

The elements of a CardLayout are stacked, one on top of the other, like a deck of cards. Read More

In java there is no "pass by reference", we have only "pass by value". When an object reference variable is passed , the value stored inside the reference variable will be passed i.e., the address of the Object that the reference variable points to... Read More

v setEditable(). Read More

Overloading: Overloading is nothing but passing the different parameters to the method. Here method name is same but parameters are different. Overriding: Overriding is nothing but giving the implentation to the method in the derived class.Here... Read More

An object reference variable holds bits that represent a way to access an object, it does not hold the object itself (it actually holds something that works a bit like a pointer to the address at which the object can be found). Read More

Swing is an extension of, and not a replacement for the AWT. There is some overlap between AWT and Swing (for example a Swing JButton component might be viewed as an improved functional replacement for an AWT Button component.) One of the advantages... Read More

According to JavaSoft, "A Java Bean is a reusable software component that can be manipulated visually in a builder tool." Read More

In Java, what is the difference between Java API & Applets. What is the advantage if a person have Java + LDAP Skills Read More

If you have the better answer, then send it to us. We will display your answer after the approval Read More

Elipse 3.0 is an sun microsystems product and it supports plugins. where Jbuilder is product of borland and it does not support plugins. Read More

Java 1.2 promises full CORBA IDL support. Read More

If you have the better answer, then send it to us. We will display your answer after the approval. If you have the better answer, then send it to us. We will display your answer after the approval. Read More

For loading the class class.forName("class name"); It just load the class only. For creating the instance for this class class.forName("class name").newInstance(); One another way for loading the class is ClassLoader. ClassLoader is an... Read More

Java supports "low-level" and "high-level" classes. "Low-level" classes provide support for socket programming: Socket, DatagramSocket, and ServerSocket classes. "High-level" classes provide "Web programming": URL, URLEncoder, and URLConnection... Read More

Tomcat is an extension to webserver. It is a servlet and jsp container. It can serve static and dynamic pages, which can be HTML and JSPs, along with servlets. Read More

Serialization is a way to convert objects (including complex data structures such as lists and trees) into a stream of bytes. Read More

The Reader/Writer class hierarchy is character-oriented, and the InputStream/OutputStream class hierarchy is byte-oriented. Read More

A class that is declared without any access modifiers is said to have package access. Thismeans that theclass can only be accessed by other classes and interfaces that are defined within the same package. Read More

You can use some open-source bug tracking software like TrackIT (http://trackit.sourceforge.net), Scarab (http://scarab.tigris.org/) or commercial software like Jira (http://www.jira.com) Read More

The most common example I can think of is a javabean. Encapsulation may be used by creating 'get' and 'set' methods in a class which are used to access the fields of the object. Typically the fields are made private while the get... Read More

List is an interface which can be used for stroing the elements in inserting order. It allows to store the duplicate elements. And for acceccing the elements, List provide a seperate iterator called ListIterator. Read More

Muliple inheritance is done with the help of interfaces interfaces Read More

An event-listener interface defines the methods that must be implemented by an event handler for a particular kind of event. An event adapter provides a default implementation of an event-listener interface. Read More

Java vs C++ 1) C++ supports pointers whereas Java does not 2) C++ supports operator overloading,multiple inheritance but java does not. 3) Java is platform independent language but c++ is depends upon operating system, machine etc. 4... Read More

Java's interface mechanism can be used to implement multiple inheritance, with one important difference from c++ way of doing MI: the inherited interfaces must be abstract. This obviates the need to choose between different implementations, as... Read More

Java.lang.Math class is a class in which all the methods are static.if some one know any other class please make an entry. Read More

The fractional part of the result is truncated. This is known as rounding toward zero. Read More

Final variale cannnot be changed.. Final method cannot be overriddden.. Final class cannot be derived. Read More

The FontMetrics class is used to define implementation-specific properties, such as ascent and descent, of a Font object. Read More

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There are several basic strategies for garbage collection: reference counting, mark-sweep, mark-compact, and copying. In addition, some algorithms can do their job incrementally (the entire heap need not be collected at once, resulting in shorter... Read More

A reachable object cannot be garbage collected. Only unreachable objects may be garbage collected. Read More

If you have the better answer, then send it to us. We will display your answer after the approval. Read More

Interface is the one which can be implemented by many number of methods in different classes as it requires, so there may be a chance that u may have some functionality which wil be need for many methods , in that case u u use interface to declare ... Read More

The equals method can be considered to perform a deep comparison of the value of an object, whereas the == operator performs a shallow comparison. The quals() method compares the characters inside a string object. == operator compares two object... Read More

Number of Processors can be known by using java.lang.Runtime.getRuntime().availableProcessors() Read More

In java, once a thread is inside a synchronized method/block , no other thread can call any other synchronized method/block on the same object. Read More

Creating and implementing an interface would be the best way for this situation. Just create an interface with empty methods which forces a programmer to implement all the methods present under it. Another way of achieving this task is to declare a... Read More

An object reference be cast to an interface reference when the object implements the referenced interface. Read More

The purpose of the System class is to provide access to system resources. Read More

When a class implements Remote interface it can not available in the client class.Thats why if we extends UnicastRemoteObject then we can rebind it through Naming.rebind("ref",objofserverclass) Read More

By using javascript In javascript we can break a string into small substring and compare each sub string . Read More

Java's security model is one of the most interesting and unique aspects of the language. For the most part it's broken into two pieces: the user adjustable security manager that checks various API operations like file access, and the byte... Read More

class serverlet_name extends HttpServlet implements SingleThreadModel { ......... ......... ......... } Read More

Yes, We can serialize the Static data also.For this we use the Externalizable tagged interface anduse writeObject() is used.Otherwise if we implement the Serializable interface if we serialize the data then static variable value is stored as zero.So... Read More

Features Java C/C++ Pointer No Yes Operator Overload No Yes Preprocessors No Yes Structures, Unions No Yes Enums No Yes Functions No (only methods within classes) Yes Goto statement No Yes Automatic Coercions No (types should be... Read More

The purpose of finalization is to give an opportunity to an unreachable object to perform any clean up before the object is garbage collected , and it is advisable Read More

Encapsulation is internal behavior, while Abstraction is External behavior Abstraction is mapping real world entity with s/w entity. By writing a class we can implement abstraction. While Encapsulation is encapsulating all properties with in... Read More

AWT - Heavy weight component. Every graphical units it will invoke native methods. SWING - Light weight component. It doesn't invoke native methods. Read More

overloading is related to one particular class.If we define two methods in the same class with same name,but different input parameters. Then it is called overloading.Overridig is related to super and sub class.He you define a method with same name ,... Read More

The digits 0 through 9 may not be used as the first character of an identifier but they maybe used after thefirst character of an identifier. Read More

Phantom memory is false memory.Memory that does not exist in reality. Read More

setBounds() Read More

ANT - means Another Neat Tools. ANT is mainly used for build serverside applictions. Read More

String objects are constants. StringBuffer objects are not. Read More

An anonymous class may implement an interface or extend a superclass, but may not bedeclared to doboth. Read More

Final member can be instantiate only at the time of declaration.null Read More

Most of the AWT-related events of the event-delegation model are defined in thejava.awt.event package.The AWTEvent class is defined in the java.awt package. Read More

A static method can be synchronized. If you do so, the JVM will obtain a lock on the java.lang.Class instance associated with the object. It is similar to saying: synchronized(XYZ.class) { } Read More

Its a kind of nested class which is NON-STATIC i.e. it has access to all var and methods of its outer class or it is fully within the scope of its enclosing class BUT the outer class to this inner class needs to create object of inner class to access... Read More

length is not a method ,It is a varaible which identifies the length of the array by subtracting one with the index position of (null)'/0'. postion of the index at present - 1 ---------> gives the len of the variable ( so... Read More

validate() Read More

The event-delegation model has two advantages over the event-inheritance model. First,it enables eventhandling to be handled by objects other than the ones that generate the events (or theircontainers). Thisallows a clean separation between a... Read More

A class that is declared without any access modifiers is said to have package access. Thismeans that theclass can only be accessed by other classes and interfaces that are defined within thesame package. Read More

No we cannot fool the JVM It willr eject the wrong one by checking class id and definitions Read More

A Canvas object provides access to a Graphics object via its paint() method. Read More

A method's throws clause must declare any checked exceptions that are not caught withinthe body of themethod. Read More

Yaa u can declare multiple main methods in different classes, this wont through any error while complition , but it through u runtime exception stating that no main method found.So there should be only one main method in a program Read More

No java does not have a pointer but we can use the new operator for ex: the name of the method is firstname we can create a objectas firstname f=new firstname this allocates the memory according to the size of the method firstname ... Read More

The JDK 1.02 event model uses an event inheritance or bubbling approach. In this model,components arerequired to handle their own events. If they do not handle a particular event, the event isinherited by (orbubbled up to) the component's... Read More

An abstract method is a method whose implementation is deferred to a subclass. Read More

com4j A Java library that allows Java applications to seemlessly interoperate with Microsoft Component Object Model. First generate Java type definitions from a COM type library. Here we are doing for the type library for the Windows Scripting... Read More

The == operator compares two objects to determine if they are the same object inmemory. It is possible fortwo String objects to have the same value, but located indifferent areas of memory. Read More

Performance does take a hit when using synchronization. I think the way to reduce this hit is to synchronize only a block of code that will be accessed by threads and not synchronize the entire method. Read More

// Replace all occurrences of 'a' with 'o' String newString = string.replace('a', 'o'); Replacing Substrings in a String static String replace(String str, String pattern, String replace) { int s = 0; int... Read More

Serialization means to convert into byte stream ,we need to serialize object so that if many thread calls that function then consistentency should be maintained. Read More

The exception propagates up to the next higher level try-catch statement (if any) orresults in the program'stermination. Read More

If you have the better answer, then send it to us. We will display your answer after the approval Read More

The event-delegation model has two advantages over the event-inheritance model. First, it enables event handling to be handled by objects other than the ones that generate the events (or their containers). This allows a clean separation between a... Read More

Java don't support Multiple Inheritance. For that we can use Interface. Interface is like the getway to comunicate between to classes. Not always we write methods in Interface, we can also create objects in the Interface. The Object which... Read More

EJB is a Server side resident resource managable, trasactional, persistable, secure, reusable component. Read More

TextField and TextArea. Read More

JDBC can't do its job without a driver, and the JDBC management layer must know the location of each and every database driver available to it. There are two ways that JDBC does this. First, upon initialization, the java.sql.DriverManager... Read More

An advantage of this scheme is that it can run in small chunks of time closely interwoven with the execution of the program. This characteristic makes it particularly suitable for real-time environments where the program can't be interrupted for... Read More

It must provide all of the methods in the interface and identify the interface in its implements clause. Read More

A static inner class behaves like any ``outer'' class. It may contain methods and fields. It is not necessarily the case that an instance of the outer class exists even when we have created an instance of the inner class. Similarly,... Read More

By implementing either the java.io.Serializable interface, or the java.io.Externalizable interface. As long as one class in a class's inheritance hierarchy implements Serializable or Externalizable, that class is serializable. Read More

A thread class may be declared as a subclass of Thread, or it may implement the Runnable interface. Read More

It is more likely that the JVMs you encounter in the real world will use a tracing algorithm in their garbage-collected heaps Read More

The Locale class is used to tailor program output to the conventions of a particular geographic, political, or cultural region. Read More

Canvas. Read More

We know how servlets and JSP's applications will be . They are all Model1 arcitectures. where we cant get the MVC (M2c) model architecture .So, we use this structs framework. And in this we can write the Business logic in Action class which is... Read More

The = operator is right associative. Read More

getLabel() and setLabel(). Read More

In reference of McCarthy : Java came from several individuals involved in the project: James gosling, Arthur, Van hoff, Andy bechtolsheim. Read More

Memory footprint : is the amount of memory a particular application is using.The JVM keeps a check on this by its sandbox mechanism. The sandbax always has the correct knowledge of the amount of space a particular program is using. Many time in real... Read More

A program's main() method takes an argument of the String[] type. Read More

All tasks must implement the run() method, whether they are a subclass of Thread or implement the Runnable interface. Read More

Question : Class hierarchy of AbstractMap is as follows "AbstractMap implements Map" Class hierarchy of HashMap is as follows "HashMap extends AbstractMap implements Map" When AbstractMap implements Map interface and AbstractMap is extended... Read More

In Java, it is ALWAYS pass by VALUE. Confusion occurs because all OBJECT variables in Java are references to objects. When we call a method in Java, the object reference is PASSED BY VALUE to the method (this means that a variable for the method&... Read More

The finally clause is used to provide the capability to execute code no matter whether or not an exception is thrown or caught. Read More

The function is implement by you but call by container it self. like the life cycle of any class like servlet init() service() destroy() and in ejb we have ejbCreate() like........... Read More

Primitive data type has a wrapper class to present. Like for int - Integer for byte Byte, for long Long etc ... Read More

main disadvantage of thread is that we need to synchronize the object while using the thread Read More

String is immutable & unchagable.In this situation String buffer provide the fact.we can modify our required string by it. Read More

 variable can be made constant only with the help of a final keyword. If you want to make it to be accessible from other classes then you need static. Read More

It is useful in cases like if u dont want to reassign second value . ex :Gravitational Force. Read More

A dead Thread can't restart not even by calling start() again on that object. Read More

Public class ThreadPool extends java.lang.Object implements ThreadPoolInt This class is an generic implementation of a thread pool, which takes the following input a) Size of the pool to be constructed b) Name of the class which implements... Read More

The GregorianCalendar provides support for traditional Western calendars. Read More

A top-level class may be public, abstract, or final. Read More

yes the JVM maitain a cache by itself.No it allocates the objects in stack ,in heap on references .Heap maintained by the JVM because every time the JVM should not use objects directly it uses only references that's why the heap maintained by... Read More

Box.Filler, Button, Canvas, Checkbox, Choice, Container, Label, List, Scrollbar, or TextComponent Read More

A Java package is a naming context for classes and interfaces. A package is used to create a separate name space for groups of classes and interfaces. Packages are also used to organize related classes and interfaces into a single API unit and to... Read More

You can use same card layout in swings also. therse is no other layout in swings. Read More

If an expression involving the Boolean & operator is evaluated, both operands are evaluated. Then the & operator is applied to the operand. When an expression involving the && operator is evaluated, the firstoperand is evaluated. If... Read More

A statement block is used to organize a sequence of statements as a single statement group. Read More

Components are the like Frame, button all these are the Component of awt package. while controllers are the events whenever we click on any button it is the controller which controls what has to do. Read More

After a thread is started, via its start() method or that of the Thread class, the JVM invokes the thread'srun() method when the thread is initially executed. Read More

The prefix form performs the increment operation and returns the value of the increment operation. The postfix form returns the current value all of the expression and then performs the increment operation on that value. Read More

Object. Read More

Java client is a user those who r developing applications or working with the java. and Java server is a JVM/JRE which r running our applications or set of instructions with the bussiness logic. Read More

The default value of the boolean type is false. Read More

Vector is a legacy class but ArrayList is not Vector is thread safe but ArrayList is not ArrayList give better performance as Vector has to suffer this due to synchronisation Read More

A public class may be accessed outside of its package. A non-public class may not be accessed outside of its package. Read More

To help you get a handle on inner classes and what they are good for, let's visit the "Stack" class.Here's a "Stack" implementation that defines a helper class, called StackIterator , for enumerating the stack's elements: public... Read More

Most of the AWT-related events of the event-delegation model are defined in the java.awt.event package.The AWTEvent class is defined in the java.awt package. Read More

if you change any sub component in a top label container then ,suppose you change some button layout in a frame then that will automatically call by paint to update to validate. that means three method will call one after another . The pack method... Read More

The range of the char type is 0 to 2^16 - 1. Read More

Numeric promotion is the conversion of a smaller numeric type to a larger numeric type,so that integer and floating-point operations may take place. In numerical promotion, byte, char, and short values are converted to int values. The int values... Read More

Class C extends A implements B { } Read More

The range of the short type is -(2^15) to 2^15 - 1. Read More

The exception propagates up to the next higher level try-catch statement (if any) or results in the program's termination. Read More

Pointers are not there mainly to avoid security threats. As JVM restricts access to the file system, but thru pointers you can access any memory location. This is the main reason, other is to avoid the complexity. Read More

Multiple inheritance is a feature in C++ by which one class can be of different types. Say class teachingAssistant is inherited from two classes say teacher and Student. Read More

Socket=port + ip in layman language socket is just like for where ip is the adress of that fort and port is the gate to enter in to that fort. server socket is the socket which present on server side basically used to listen request from... Read More

It is essential to catch/declare throws clause for checked exceptions. Unchecked exceptions need not be handled. Read More

A thread is in the ready state after it has been created and started. Read More

Date date = new Date(); Calendar cal = new GregorianCalendar(); date=cal.setTime(Calendar.DAYS+10) date=cal.getTime(date); Read More

The java.awt.AWTEvent class is the highest-level class in the AWT event-classhierarchy. Read More

A thread can enter the waiting state by invoking its sleep() method, by blocking on I/O, by unsuccessfully attempting to acquire an object's lock, or by invoking an object's wait() method. It can also enter the waiting state by invoking its... Read More

Delegation is an alternative to inheritance. Delegation means that you include an instance of another class as an instance variable, and forward messages to the instance. It is often safer than inheritance because it forces you to think about each... Read More

A task's priority is an integer value that identifies the relative order in which it should be executed with respect to other tasks. The scheduler attempts to schedule higher priority tasks before lower priority tasks. Read More

Integer / and % can result in the throwing of an ArithmeticException. Read More

Public static void main(String args[]) Here we helping the jvm to call main method without any object that is why main is declared as public static. Read More

Inheritance is a class extending another class. Abstraction is an inteface implementing another interface, so that a class implementing the interface A whch implements interface B should provide the implementation for all the methods in interface A... Read More

The CheckboxMenuItem class extends the MenuItem class to support a menu item that may be checked orunchecked. Read More

A layout manager is an object that is used to organize components in a container. Read More

When an object is created, all its fields are set to default initial values for their respective types(zero for all numeric types, false for boolean, u000 for char, and null for object reference.) Then the constructor is invoked. Each constructor... Read More

An uncaught exception results in the uncaughtException() method of the thread's ThreadGroup being invoked, which eventually results in the termination of the programin which it is thrown. Read More

We can give semicolon at the end of the class. but it is not necessary, generally we will not use because java uses } as the end of the class, semicolon for end of the statements Read More

The default value of an String type is null. Read More

A dead thread cannot be restarted. Read More

Provide a constructor to initilize the variable and remove the mutator method ( setter method) for that variable. Read More

Constructor nesting can be achieved by using : this(parameters....) constructors with parameters can use the above to delagate calls to a non argument constructor and vice versa. Read More

A thread enters the waiting state when it blocks on I/O. Read More

Question : i want to know the difference between these two programs mean the flow /*public class Aquestion { private int i = giveMeJ(); private int j = 10; private int giveMeJ() { return j; } public static void main(String... Read More

Order of precedence determines the order in which operators are evaluated in expressions. Associatity determines whether an expression is evaluated left-to-right or right-to-left. Read More

All AWT event listeners extend the java.util.EventListener interface. Read More

By using notify() or notifyAll() method we can release the lock.But notify() method sometimes notify unwanted thread.So in some situation notify() method is avoidable. Read More

Question : Can You catch the Error? 2. Difference between compiletime exception and runtime exception? 3. How you throw user defined exception? 4. How you handle throwable while using exceptions ? 5. What are the methods... Read More

A compilation unit is a Java source code file. Read More

The Enumeration interface is what allows you to walk through the elements of a legacy collection(ie., for Synchronized Collections). Iterator interface is used for stepping through the elements(.ie., for ArrayList,LinkedList). Read More

A variable's scope is the region of a program within which the variable can be referred to by its simple name. The location of the variable declaration within your program establishes its scope and places it into one of these four categories... Read More

 native method is a method that is implemented in a language other than Java. Read More

Clipping is the process of confining paint operations to a limited area or shape. Read More

Question : I want to know output of this program and the flow also public class Aquestion { private int i = giveMeJ(); private int j = 10; private int giveMeJ() { return j; } public static void main(String args[]) { ... Read More

It is right shift operator, which will produce divide by 2 action. For example 10>>2 will produce 5. the binary value of 10 is "1010" if we right shift the above by one position it will be "0101" this is equivalent to 5. Read More

Question : what is assert function what are the type how they are used with an example Answers: An assertion is a statement in the that enables you to test your assumptions about your program. Syntax: assert Expression1 :... Read More

Question : Write a java standalone program / method to take out all the special characters in the string provided below. // ASCII a ? z (97 ? 122) String sSENTENCE = ?This!is^a$t*e)s|t?;      Answers: class... Read More

We can have connection pool used for such cases like for DB connections. For each thread accessing the DB, one connection object will be taken from the connection pool and will be given to the thread.Once the job is done the object goes back to... Read More

The == operator would be used, in an object sense, to see if the two objects were actually the same object. This operator looks at the actually memory address to see if it actually the same object. The equals() method is used to compare the values... Read More

Even calling the garbage collector method doesn't ensure that garbage collection will take place. Its just a request method. Read More

Question : The following code is executed by a multi-threaded environment: public void functionOne() { System.out.println("Staring itrs= " + this.cntr); for( int i=0; i<this.cntr; i++ ) { System.out.println("iteration: " + i); } ... Read More

Creating a new class is simply creating a class with no extensions and no implementations. The signature is as follows public class MyClass() { } *Extending a class is when you want to use the functionality of another class or classes. The extended... Read More

The java.lang package is always imported by default. Read More

The paint() method is called each time a Applet must be redrawn. Read More

In java.lang package Object class is there which is the super super class of all class in java language so in order to import that jdk soft implicitly provides Default package Read More

To reduce possibility of memory leaks, following things should be kept in mind. Try to avoid long recursive loops in the code. This leads to an OutOfMemoryError. Avoid collections as static members of a class. If so, carefully manage... Read More

The Canvas, Frame, Panel, and Applet classes support painting. Read More

You can have any number of curly braces inside any(main as well as other) functions but each and every brace should have matching close brace. Also you can have any number of semi colons(;) The following program compiles and print the message ... Read More

Panel. Read More

The File class encapsulates the files and directories of the local file system. The RandomAccessFile class provides the methods needed to directly access data contained in any part of a file. Read More

The JVM is core for JAVA programing , When you are trying to run applet or Frame based Application(developed by applet or swing ) there JRE Should be there. With out JRE ,you can run the simple java code which dont have any applet or swing... Read More

Servlet: we used to call HTML in java program JSP: we call java in HTML this is the simple logic, i dint in touchup with the presentation and application sketches. Read More

We can store elements in arraylist by using index Read More

 package statement must appear as the first line in a source code file (excluding blank lines and comments). Read More

First servlet looks for the service() method.If in the case service() method is not present in that appilication, then looks for the doPost() method.If doPost() method is also not present in your appilication ,then servlet looks for the doGet()... Read More

While overriding, methos in subclass can not throw any new checked exception. it can only decalre exception already declared in the super class or its subclasses. since Airthmetic exception is an unchecked exception it can be declared without any... Read More

Java is a platform independent but it has some drawback it is not thread independent and garbage collection independent because of that drawback we are not able to controll some real life applications like to controll plane, to controll nuclear power... Read More

In ovveriding in subclass the access specifier should be less restrictive. if protected is used in super class then in sub class u can use public and protected both but not private. if u try to use private it will not be compiled. Read More

Question : whats the difference in data types of java and c++? 2)what is the use of finally block?? 3)what is encapsulation in oops?how is it achieved in Java?     Answers: The types supported by Java are the primitive data... Read More

No. Read More

FINAL for a variable : value is constant. FINAL for a method : cannot be overridden. FINAL for a class : cannot be derived. Read More

In class level the most exclusive lock can be achieved by synchronising the class's class object and declaring it static. Read More

The volatile keyword is used on variables that may be modified simultaneously by other threads. This warns the compiler to fetch them fresh each time, rather than caching them in registers. This also inhibits certain optimisations that assume no... Read More

The == comparator simply checks to see that two primitives are equivelent by virtue of memory location. The equals( ) method will actually check to see that the values of the two objects are equivelent. A good rule of thumb is to always use the... Read More

Run time polimorphism means function call is resolved at run time.It means which function code will execute in response to a perticular function call is not known till execution of program.ex- Funtion overriding. Compile time polimorphism means... Read More

The >> operator causes the bits of the left operand to be shifted to the right, based on the value of the right operand. The bits that fill in the shifted left bits have the value of the leftmost bit (before the shift operation). The >>... Read More

setBounds(). Read More

The start() method of the Thread class is invoked to cause an object to begin executing as a separate thread. Read More

Break statement A statement that terminates the current loop iteration and causes execution to break out of a loop. Continue statement A statement that terminates the current loop iteration and persists the loop with the next iteration. Read More

Byte code is simply the converted source code into arrays of bytes and generated after compilation of source code and is understandable only for interpreter or you can say java run time environment. Unicode is character standard to represent... Read More

Following Severs are avilable 1 Tomcat Apatche 2 IIS 3J2ee 4 Jboss 5BEA WebLogic Server 6iPlanet 7 Oracle 8Orion Server 9 WebSphere 10NetDynamics 11JRun Server 12Tomcat 13JOnAS 14Pramati Server 15Power Tier for J2EE Read More

The Iterator interface is used to step through the elements of a Collection. Read More

A (non-local) inner class may be declared as public, protected, private, static, final, orabstract. Read More

s, we can get the output by throws exception method. that is by extending throws exception from the class method defined. Read More

SetBounds(int x, int y, ing width, int height): It is a method of a component to location and size a component. But it will work only when the container doesn't have any one of default managers. If a component already has any one of... Read More

U can do this by using the methods getBlob(int i),getBlob(String col),getClob(int i),getClob(Strin col) of the ResultSet Read More

It uses those low order bytes of the result that can fit into the size of the type allowed by the operation. Read More

The == operator compares two objects to determine if they are the same object inmemory. It is possible for two String objects to have the same value, but located in different areas of memory. Read More

A final variable is the one whose value cannot be changed. It is a constant. Read More

The List interface provides support for ordered collections of objects. Read More

The JDK 1.02 event model uses an event inheritance or bubbling approach. In this model, components are required to handle their own events. If they do not handle a particular event, the event is inherited by (or bubbled up to) the component's... Read More

The inner class cannot access the parameters of the function in which it defined, unless the keyword "final" is not used with them. Read More

The digits 0 through 9 may not be used as the first character of an identifier but they may be used after the first character of an identifier. Read More

A method's throws clause must declare any checked exceptions that are not caught within the body of the method. Read More

A framework is collection of interfaces and classes. java.util.Collection package having enough interfaces and classes to make them as a framework. in short framework is developed standard library Read More

Memory leak is when memory used by an object or variable cannot be freed even after the code that created the object/ variable has finished execution. According to wikipedia: Memory leaks are often thought of as failures to release unused memory by... Read More

Declaring a Transient Variable You use the transient keyword to indicate to the Java virtual machine that the indicated variable is not part of the persistent state of the object. Variables that are part of the persistent state of an object... Read More

In general, applets loaded over the net are prevented from accessing files on the client machine, and from making network connections except to the host originating the applet.In addition, applets loaded over the network are prevented from starting... Read More

The Panel and Applet classes use the FlowLayout as their default layout. Read More

yes, you can get the address from the hasCode of the Object class. Read More

u can try with gridlayout(no of columns,no.of rows) set GridLayout(5,2) When u set ur components here, ull get on the order, of 5 x 2. if u want to put entire things in to order, FlowLayout() is usefull Read More

The preferred size of a component is the minimum component size that will allow the component to display normally. Read More

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Wrapper class is class that allows us to access primitive data types as objects. Read More

To make the applet talk to the servlet you need to use HttpURLConnection. Open a URLConnection from an apple to the sevlet by using the url path of the servlet in the applet. Then use InputStreams to the servlet and write you data to the... Read More

MVC Model View Controller This is basically an architecture that is used to stress the reusing object oriented concept that will be conducive for programmer as well others. You can use more than one controller.As when you undergo different kind... Read More

In object class it contain some methods like hashCode(), toString() methods. this two methods is used to give some information. for example in my project devlepoment i use several classes at some point time i get confused what sort of information i... Read More

java does not support Multiple inheritance because 1. If the two super classes(multiple interitance contain more than one super class) has same method, there is confusion in accessing the method 2. in other hand, in the same scenrio, the first... Read More

Yes we can serialize the static variable.if u don't want to serialize, u need to declare the variable as transient Read More

Most of the AWT-related events of the event-delegation model are defined in the java.awt.event package. The AWT Event class is defined in the java.awt package. Read More

Event delegation model allows other objects to handle the events rather than the objects on which they were produced, Also uneccessary events are not handled. Read More

Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated it invokes the update() method of each of its observers to notify the observers that it has changed state. The Observer interface is... Read More

2 bytes, signed (two's complement), -32,768 to 32,767 Read More

Streams are the rooted ,specific connections between the source and aplication.input stream are the connection between source to application and vise varsa.the input stream and outputstream aer the sub class of byte stream.they only transfer the... Read More

The non-Unicode letter characters $ and _ may appear as the first character of an identifier. Read More

Threads block on i/o (that is enters the waiting state) so that other threads may executewhile the i/o Operation is performed. Read More

Question : let say there are two interfaces like the following interface int1{ int meth1(); } interface int22{ int meth1(); } ok then i am implementing both of them in a calss as follows class mycl implements... Read More

1.Vector and Arraylist are grownable or shinkable where are array is not. 2.Vector and Arraylist are implemented from List interface where as array is a primitive data type 3.Vector is Synchrnized where as arraylist is not 4.For best... Read More

Question : In client-server approach, how to get an IP address of remote machine, and how we can find whether tht machine is connected with server or not. I hv found one solution is pinging in background, but how we can do such pinging? how... Read More

Component. Read More

The CheckboxMenuItem class extends the MenuItem class to support a menu item that may be checked or unchecked. Read More

Synchronization is a process of letting one thread to access the method while all other thread are waiting, which avoids deadlock Read More

Stub: Stub is a client side proxy,the duty of stub is to convert the java code into bit-blobs streams(Network oriented stream).This is also known as "Marshalling". Skeleton: Skeleton is a server side proxy,the duty of skeleton is to convert the bit... Read More

It is platform independence. The client can get assurance that his application can work on any OS. It is hardware independence. It is Secured, Robust and portable. The main advantage of java is it is open source i.e the user no need to... Read More

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Please Stop using JAVA 1.2 Coz there are many methods which are deprecated in Java 1.4. For thread stop, suspend are deprecated in JAva 1.4 Read More

class A { public void show(){System.out.println("A");} } class B { public void show1(){System.out.println("B");} } class c { A a=null; B b=null; c() { a=new A(); b=new B(); } public void show2() { a.show(); b.show1(); } } ... Read More

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A variable's data type determines the values the variable can contain and the operations that can be performed on it. The Java programming language has two categories of data types ? a)Primitive b)Reference(A data element whose... Read More

Using the autocommit method provided by the connection object. Read More

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Java does not support Pointers, C++ support pointers. Java does not support structures and unions as C++. In C, code is organized into functions, which are global subroutines accessible to a program. C++ added classes and in doing so provided... Read More

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Char is unsigned so its minimum value is 0. It can't be negative. Read More

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After thread stops processing and has completed its run method it enters a dead state. Dead here signifies that it may no more "excute". Though it still remains to be a notmal java object in memeory n u can call other non-thread specific methods on... Read More

Object is the root class of all java classes.It is the mother of all classes Read More

A static variable is associated with the class as a whole rather than with specific instances of a class. Non-static variables take on unique values with each object instance. Read More

Import is used to import .ie bring ur java packages to ur source(like io, sql and net packages) The classpath is one where, u need specify the path of the jvm to ur class file Read More

java is purly object oriented programinglanguage because u said that primitivr data types like int and char are used but these int ,char and soon are the objects of class Class plase refer to api document of j2se Read More

RegisterDriver() registers the JDBC driver with the DriverManager class. Class.forName() first loads the respective driver into the memory, registers the driver with the Driver Manager class and then creates an instance of the driver to carry... Read More

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Stub: Stub is a client side representative.The functionality of stub is Marshalling and Unmarshalling in RMI(Remote method invocation). Submitted by Chinnakotla Devarathnam (devarathnam@yahoo.co.in) Read More

Java uses layout managers to lay out components in a consistent manner across all windowing platforms. Since Java's layout managers aren't tied to absolute sizing and positioning, they are able to accomodate platform-specific differences... Read More

An inner class is a type of nested class that is not explicitly or implicitly declared static. Types of Inner Classes: Local inner class. Anonymous inner class. Non-static member class. Member Inner class. Read More

How to preventing inheritance:by a class declared as final then that calss cannot be inheritedwhen preventing the inheritance:suppose iy ur class no need to reused then only u can declare final . Read More

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A Servlet is a component that extends the functionality the server. The service() method of the servlet takes in 2 paramaters HttpServletRequest and the HttpServletResponse objects. Read More

A package statement must appear as the first line in a source code file (excluding blanklines and comments). Read More

Parameter are passed in RMI using Parameter marshalling. As RMI is used to invoke remote objects, many of the times objects, their references have passed across the network. Hence these objects need to be serialized. Read More

Question : What is difference between runnable and thread ? why we use static class             Answers: Difference between Runnable interface and Thread comes with in the main() method.If our class is... Read More

Garbage collection does not guarantee that a program will not run out of memory. It is possible for programs to use up memory resources faster than they are garbage collected. It is also possible for programs to create objects that are not subject to... Read More

One of the "clean" features of the Java programming language is that it mandates a separation between interfaces (pure behavior) and classes (state and behavior). Interfaces are used in Java to specify the behavior of derived classes. Often... Read More

Yes , We can send objects using a Socket. Read More

Consider Class A extends Class B. If Class B has protected constructors then 1.Cannot create object from Class A directly. 2.Indirectly you can create object of Class A by instantialting Class B. Read More

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Java API contains the class DriverManager and the interface Driver in java.sql package. This class provides information about the drivers and database to connect. Read More

AJAX stands for Asynchronous JavaScript And XML. Without AJAX, client has to submit the web page to interact with the server. But using AJAX, client side Java Script code can call server asynchronously and receive the results in an XML format.... Read More

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It does not return null value. it return -1when it reaches the end of file Read More

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JVM is a platform-independent programming language that converts Java bytecode into machine language and executes it. Read More

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A singleton is a class for which only one instance can exist within a program. In other words, only one, single object of that particular class can be created in a program. Read More

Wrapper classes are used to convert one data type into another data type Read More

Thread class is a class having defined methods for thread implementation & runnable is an interface where methods needs to be defined as required Read More

A (non-local) inner class may be declared as public, protected, private, static, final, or abstract. Read More

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Collection framework provides set of classes and interfaces to work with group of objects. The collection framework mainly provieds three interface classes Set, List, and Map. Set's Implementation are HashSet, TreeSet and LinkedHashSet.... Read More

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For a pure object oriented language,there should be 6 features available with it.They are:- 1.Encapsulation/Information Hiding 2.Inheritance 3.Polymorphisms/Dynamic Binding 4.All pre-defined types should be Objects 5.All operations performed... Read More

When a thread blocks on I/O, it enters to BLOCKED state. A thread enters WAITING state, while a thread calls wait(), and it will come back to READY state, while other threads call notify() or notifyAll(). The wait-notify model is called monitor... Read More

No answer available currently. Be the first one to reply to this question by submitting your answer from the form below.   Read More

The digits 0 through 9 may not be used as the first character of an identifier but they maybe used after the first character of an identifier. Read More

Java language can stand on its own and creates "standalone" applications while JavaScript must be placed inside an HTML document to function. Java must be compiled into what is known as a "machine language" before it can be run. You can alter... Read More

Following is the order of invocation: 1) init(); 2) start(); 3) stop(); 4) destroy(); Read More

String object are immutable so they are not garbage collected all kinds of objects are garbage collected except string object so try to avoid the usage of string objects in a large application Read More

An enterprise Bean is a body of code with fields and methods to implement modules of business logic. Client programs interact with one or more Beans, and an enterprise Bean can be implemented to interact with other enterprise Beans. An enterprise... Read More

Default buffer size is 16characters Read More

Native methods are methods that are defined as public static methods within a java class, but whose implementation is provided in another programming language such as C. Read More

The Java API (Application Programming Interface) is like a super dictionary of the Java language. It has a list of all Java packages, classes, and interfaces; along with all of their methods, fields and constructors; and also with information on how... Read More

Question : what are the other ways to prevent a class from being subclassed.one way is to declare the class final. does declaring a class private prevent it from being subclassed?  Answers: I just tried out compiling a class... Read More

Synchronize is used when u want to make ur methods thread safe. The disadvantage of synchronise is it will end up in slowing down the program. Also if not handled properly it will end up in dead lock. 1. Only use (and minimize it's use... Read More

The difference between unicast and multicast is that in unicast approach the sender sends the data stream to a single receiver at a time. Thus there is one to one communication. In a multicast the sender and the interested receivers communicate.... Read More

class NoMoneyException extends Exception{ public NoMoneyException(String m){super(m);}} public class Bank { public static void main(String[] args) throws NoMoneyException{ int b=5000,wd=15000; if(b>wd){System.out.println("Enjoy");} else ... Read More

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By using static inner classes, you can add additional support functionality to your systems for capabilities such as testing, while incurring no penalties in normal, production deployment Read More

Not necessarily does it wait for the memory to be fully allocated. The garbage collection thread is looking at what percentage of available memory is already allocated..and if the memory allocation goes above a perticular level..say 80 %, the gc... Read More

One of the "clean" features of the Java programming language is that it mandates a separation between interfaces (pure behavior) and classes (state and behavior). Interfaces are used in Java to specify the behavior of derived classes.Often you... Read More

Any time you use system calls specific to one operating system and do not create alternative calls for another operating system, your program will not function correctly. Solaris systems and Intel systems order the bits of an integer differently. ... Read More

Classpath: The CLASSPATH is an environment variable that tells the Java compiler javac. exe where to look for class files to import or java.exe where to find class files to interpret. Path: The PATH is an environment variable that tells the... Read More

I beleave this question is belonging to ejb. Home interface is an interface acts like a create factory. JNDI is stands java naming domin interface. Read More

As per the Java convention and guide lines every class declared as public must be defined individually in a single file. If we have two public classes then we need to have to separate files for them. We can not put them in a single Java file. If you... Read More

JIT means Just In Time compiler.The JIT used to compile java source file and generate class files.The execution engine means Java Virtual Machine( JVM) which executes the class files Read More

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The Single Thread Model is an interface which is used to indicate that only a single thread will execute the service( ) method of a servlet at a given time. It defines no constants and declares no methods. If a servlet implements this interface, the... Read More

Question : What is interface? and what is the purpose of it? Iknow lot of people having problem in this question(even i have it). so i request some good answer to come.I need a good example for the purpose of interface      ... Read More

Interfaces are used when we have to develop distributed applications or when we need to implement multiple inheritence. While abstract classes will be used when we need to develop a standalone application. Read More

All are use when we want to handle Objects, alougth difference is ArrayList contains objects in any order while with LinkList objects are stored in the order which you entered, but both are not thread safe. Vector is similar to ArrayLias but is... Read More

ArrayList is not Synchronized. Hence in multithreaded programming use ArrayList While Vector is Synchronized. So if we have a Banking ATM transaction where u dont want 2 people to access the same account at the same time in 2 different m/c use Vector... Read More

Start method is method of Thread which is implemented for create and run thread. Which will call run() where you put your implementation. If you directly call run() method it is just normal method call and not a new thread. That call will be in main... Read More

To incorporate multiple inheritence in Java Application. 2. To Develop Distributed applications. Interfaces provide more sophisticated ways to organize and control the objects in your system. The interface keyword takes the abstract concept one... Read More

In the Java world, serialization is the storing of an object's current state on any permanent storage media for later reuse. This is done using when you use the seriazlizable interface or when using the ObjectOutputStream and ObjectInputStream... Read More

Java Native Interface: It defines the way that a Java program can call programs written in languages like C. Read More

There are some ways to Pass a value from a Html page to the servlet.. 1. hidden variable 2. appending to the link by usign name value pair. Read More

The object class is super or boss class of all classes in java all the classes by default extends this class and can uses the methods of these classexmp. equals,compareto etc Read More

This site is very useful for freshers yor are applying for the jobs in software side and also useful to gain knowledge in programming side and we know about the all programming language and gaining with important hints and important question its... Read More

Paint is called for the first time the applet is loaded, whereas repaint method is called everytime the applet is refreshed. Read More

Garbage collection is one of the features of java... Java provide automatically releasing of the object if that is no longer in the use. so that the memory can be used by some other object.. garbage collector collect the oblect only those whose... Read More

The heap is the runtime data area from which memory for all class instances and arrays is allocated. The heap may be of a fixed size or may be expanded. The heap is created on virtual machine start-up. If you have complicated algorithms or big... Read More

server object is first loaded in the memory.... Read More

Question : We know that Object class is super class of every class & a class extends only one class. so how is it possible to a class to extend other than Object class? Answers: case 1 suppose you have a class Test,... Read More

Coz after extends keyword you can specify only one class name, coz no default delimerters are present in java Read More

Java 1.2 promises full CORBA IDL support. Read More

According to JavaSoft, "A Java Bean is a reusable software component that can be manipulated visually in a builder tool." Read More

(i guess) This depand on the operating system. like windows Xp support support multithreading. so if you startig a 3 notepad in XP it's treated as three threads. Read More

Obviously one should ideally go for an interface.Coz as we all know one can only extend just 1 class , where as one can implement as many interfaces as one can.And in case the class under contention has got some threads to invoke or if it is some... Read More

The following modifiers may be used with a top-level class: private, protected or public access modifiers and/or either abstract or final (not both). Read More

java.sql.*; ,javax.servlet.*; Read More

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ArrayList is a part of the Collection Framework.We can store any type of objects, and we can deal with only objects.It is growable.Array is collection of similar data items.We can have array of primitives or objects.It is of fixed size,We can have... Read More

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A Class is nothing but a byte code which will be generated when you compile a java file. And it is required to execute your java file. Where as a ClassLoader is also a class which loads the class files into memory in order for the Java programs to... Read More

Java provide a automatic clean up of object if that object referecne counter becomes zero. and this is done by the garbage collector. this will invoke automatically and free all those resources(object) who is not been use for a long time.. Read More

This class implements the set interface, backed by a hash table (actually a HashMap instance). It makes no guarantees as to the iteration order of the set; in particular, it does not guarantee that the order will remain constant over time. This class... Read More

Question : Why clonning method is private? can u overload the main() method. 2)can overload the run() method. 3)what is Common Separated value. Answers: in java objects are created by 2 methodes, 1>by creating... Read More

Stub: Stub is a client side proxy. Skeleton: Skeleton is server side proxy. The functionality of stub and skeleton is Marshalling and Demarshalling. Marshalling : It is a process of converting the java data into byte stream. Demarshalling:... Read More

Question : why java does not support inheritance of multiple superclasses? what is achieved by inheritance? why there is no main method in servlets/jsps?       Answers: Handling the two classes always be a... Read More

It is written x ? y : z. Read More

Question : What is collection framework?what interfaces and classes support collection framework?       Answers: A Collection Framework is a generic types which you use to create collection classes that support... Read More

Hyper text transfer protocol(HTTP) is used for communication between client and server. Submitted by Chinnakotla Devarathnam (devarathnam@yahoo.co.in) Read More

Question : what is difference between instance and object.? what are the all difference between interface and abstract class? Answers: Instance means just creating a reference(copy) . object :means when memory location... Read More

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AWT is a "Heavy weight" component require native OS. Swing components are called "lightweight" because they do not require a native OS object to implement their functionality. Read More

When a String is created, it is not destroyed. It remains in the pool of memory and whenever that string is referred, the JVM searches for the String from the string pool of memory and gets the relevant data. So as such String is expensive... Read More

The Java Foundation Classes (JFC) are a set of GUI components and other services simplifying the development and deployment of desktop and Internet/ Intranet applications. Java Foundation Classes (JFC) Read More

RMI: REMOTE METHOD INVOCATION(RMI) it is a mechanism to invoke the methods from one JVM( Java virtual machine) to another JVM. SOCKET:It is a perfect end point.Mainly it is used in the networking.or it is a destination point. Submitted by... Read More

JComponent Read More

Daemon thread is a kind of threads: normally it will run forever, but when all other non-daemon threads are dead, daemon thread will be killed by JVM Read More

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JIT is just-in-time. Yes JIT is bundled with JDK. Compiler converts .java file into .class file then interpreter reads bytecodes and that's why JIT. Read More

The code in a static block is loaded/executed only once i.e. when the class is first initialized. A class can have any number of static blocks. Static block is not member of a class, they do not have a return statement and they cannot be called... Read More

The code in a static block is loaded/executed only once i.e. when the class is first initialized. A class can have any number of static blocks. Static block is not member of a class, they do not have a return statement and they cannot be called... Read More

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The "update" method is an internal method belonging to one of " applet's" parent-classes. When you call "repaint" this method is called. It Read More

where and when we use abstract class and abstract methods Read More

java.sql.*; javax.servlet.*; Read More

RMI is completely Java based, where CORBA is language independant. There are many adapters for CORBA, and programs can call processes written in any language that has a CORBA interface. CORBA has many more features documented in the specification... Read More

Static variable are loaded when classloader brings the class to the JVM. It is not neccessary that an object has to be created. When u access any of the static variable or static methods then the class will be loaded. Read More

The simplest way for an applet to exchange information with a servlet is through an HTTP text stream. Another, less common strategy for applet-to-servlet communication is to create a raw socket connection from the applet back to the servlet. Read More

Question : While developing one in JSP page we are sending request to Struts frame work.If we click two times submit button then First time only it should accept request and second time should reject that request in struts frame work. How... Read More

we can't implement interface in JSP. This one of the major difference between Servlet's and JSP's. Read More

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A process is an OS-level task or service. A thread runs "inside" a process and may be virtual or simulated. Generally speaking, threads share resources like memory, where processes each have their own separate memory area, and need to take more... Read More

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Java supports exception handling by its try catch constructs. Java API define exception classes for such conditions. These classes are derived from java.lang.Throwable class. User defined exceptions are those exceptions which an application... Read More

J2EE application modules (.ear), EJB modules (.jar) and web application modules (.war). Read More

Constructor can not be inherited because inheritance feature is only available for class not for methods (constructor is nothing but method) and all methods of super class is available for sub-class. Read More

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In a j2ee application there are possibly following tiers. Client Tier - Contains client side applets. Web Tier - Contains web components jsp, servlets. Application tier - contains business logic ejbs. Legacy Application tier -... Read More

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Funda ? Dynamic Memory Management. Some of the important differences between Java and C or C++ is how they handle memory. Java eliminates pointers and adds garbage collection and true arrays to the language. C uses pointers for memory management... Read More

Java 2 Platform, Enterprise Edition (J2EE) defines the standard for developing component-based multitier enterprise applications. Read More

Abstract class must be extended/subclassed (to be useful). It serves as a template. A class that is abstract may not be instantiated (ie, you may not call its constructor), abstract class may contain static data. Any class with an abstract method is... Read More

UML provide us notation and keywords. Read More

Benifits of Swing over AWT: 1.Swing is a peerbased technology. 2.Swing allows light-weight components. 3.Swing components are "look and feel." 4.Swing components lightly dependent on underlaying domain. 5.Swing components will be appeared as... Read More

A class loader is an object that is responsible for loading classes.The class ClassLoader is an abstract class. Read More

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There are four levels of access specifiers in Java. They are Public, Private and Protected. an default. PUBLIC: If the method or the variable is declared public, then it will be visible to all classes of the program. PRIVATE: If the method or the... Read More

Anonymous: instantiating the class without object name. Singleton: it can instantiated by only one time. Assertions: to show warning to the user. Read More

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A Scrollbar is a Component, but not a Container. A ScrollPane is a Container. AScrollPane handles itsown events and performs its own scrolling. Read More

When a task invokes its yield() method, it returns to the ready state. When a task invokes its sleep() method, it returns to the waiting state. Read More

Type1: sun.jdbc.odbc.JdbcOdbcDriver type4(thinDriver):jdbc:"oralce:thin:@localhost:1521:oracle","scott","tiger") It is fastest Driver,it uses java sockets to direct connect with oracle.it is 100%pure java.this is 100% platform independent. Read More

An input stream produces a stream of characters; an output stream receives a stream of characters, ?one at a time.? Read More

The solution is Map m=Collections.synchronizedMap(new HashMap(..))---ramanan-- Read More

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The difference is that a HashMap stores all of its data inside of a hash table while a TreeMap stores all of its information in a tree. Read More

I work on Java/j2ee with weblogic server. I face some problems to run the servlet programs and in J2ee entity bean program. So, i want to the exact procedure of execution. Read More

In simple terms, an applet runs under the control of a browser, whereas an application runs stand-alone, with the support of a virtual machine. As such, an applet is subjected to more stringent security restrictions in terms of file and network... Read More

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The Comparable is for natural ordering and Comparator is for custom ordering. But we can override the compareTo method of comparable interface to give a custom ordering. Read More

WEBLOGIC: is a application server. Supports many protocols. Used for enterprise applications and EJBs. Supports N-Tier architectures. Provides more scalability. TOMCAT: is a web server supports only HTTP / HTTPS protocols Used for... Read More

Because the multiple inheritance causes the redundancy coz the size of the childs increases Suppose node derived from the multiple node causes the same method will be inherited in the that node so avoid redundancy.... In interfaces we just have... Read More

A layout manager is an object that is used to organize components in a container. Read More

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Question : What is the difference between Model Data and Default Model Data Answers: Modal Data is a interface while DefaultModalData is a abstract class which implements ModalData. Read More

The simple Try statement comes before the block of code, the Catch block of code is where we specify what type of error to look for, and the Finally block of code is always executed and contains cleanup routines for exception situations. Since the... Read More

The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected. Read More

Struts Framework based on MVC Design pattern.M, the model Component which has all the business logic in it and V - View is for the Presentation. Jsps form the presentation part of it. JSPs contain any combination of Struts custom tags.The org.apache... Read More

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Reflection is an advanced feature of the Java environment. It gives runtime information about objects, classes, and interfaces. Uses :Constructing an object using a given constructor Invoking an object's method using such-and-such... Read More

No interface is implicitly implemented, 'coz once you implement some interface u should implement all the methods of that interface. Read More

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In think there is no direct mechanism to provide validatations. If you are talking about the Swing/AWT the validations there is no API as of my knowlege. But when u talk about web based applcations most of the validations are done with the... Read More

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Java Mail Api provides capability to a java application. to read and write emails using smtp , pop3 , imap etc Read More

Servlet can not be used as a business logic component which EJB can be used. Read More

To write our own Exception class 1)Our class must be subclass of Throwable or Exception class 2)Evert Exception class provide 2 constructors a) no arguments b) one argument i.e String argument 3) Optional: Overidding toString metod of... Read More

An object must implement the Serializable or Externalizable interface before it can bewritten to a stream asan object. Read More

If two threads can both execute a method that modifies the state of an object then the method should be declared to be synchronized, allowing only one thread to execute the method at a time. Read More

All swing components are derived from abstract javax.swing.Jcomponet class. Read More

since swings are light weight components and AWT is heavy weight component swings are fster than AWT and swings are platform independent were as AWT is not platform independent Read More

class is declared abstract for extended clarity. If any method in the class is declared abstract then the class has to be declared abstract and the method has to be implemented in the following derived class. Read More