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What is the difference between an instance and an object in Java?
raghavleo
- Jul 4th, 2008
In general we think instance and objects are same, but they are incorrect.instance will have the both class definiation and the object defination where as in object it will have only the object defina...
AjayMukiri
- Apr 30th, 2008
Instance and Object are same as per my knowledgeCreating an Instance of a class is creating an object onlyA a = new A() --Here "a" is an instance of a class A, on same time "a"...
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What is the name of the java compiler used to compile the source file to a byte code?
vawani
- Nov 5th, 2008
There is no specific name for it, its only JAVA COMPILER and you can find it by the name javac.exe which you are providing the class path at the compilation or at the system properties--> Advanc...
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How to transfer data from one web application to another web application which are present in the same container in java?
meetpavy
- Sep 24th, 2008
This can be done by establishing URL Connection between the respective applications using java.net.URLConnection. Once connection is established requests can be wrote using ObjectOutputStream. I...
sampra
- Feb 22nd, 2008
Using the URL pattern we can transfer data from one web application to the other web application
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Servlets are multi threaded by default. If there are concurrent requests to the same servlet the servlet container generates another instance of the servlet . Is this the reason y servelts are multi threaded by default?? Is there any way the multi threaded feature can be achieved ?
vinaymudgil007
- May 21st, 2008
one thing surely i can say and that is "only one insatnce of the servelet would be created" and multiple threads would be used to serve the request.......well if the requests are very large ...
AjayMukiri
- Apr 30th, 2008
Servlets are multi threaded by default. If there are concurrent requests to the same servlet the servlet container generates New Thread . So this the reason servelts are multi threaded by default.
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Why wait and notify method in Object class
Why wait and notify method in Object class, why these are not in Thread Class.
sujithkthomas
- Nov 13th, 2009
Inter thread communication is not directly supported?by the producer or consumer, but by the object they are acting upon. Also lock is associated with a particular object. If a thread needs a lock it use sync block and release using object's methods.
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What's the difference between Object and "E"?
I'm trying to write an Iterator class for a LinkedList class that I wrote.One of the methods is "public E next()"I try to return an "E" but eclipse says "cannot convert from Object to E".How do I fix this?
kabir soni
- Feb 6th, 2009
Object is a class and E is a generic type parameter . And Iterator class alwayes return Object so to fix this problem, you need to call it. For exampleimport java.util.ArrayList;import java.util.Itera...
shishir11485
- Aug 5th, 2008
Object having a reference of one variable store in stack whereas "E" is created in a heap don't have a reference variable
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Platform and Machine Dependency
What is the difference between platform dependency and machine dependency?
tamil_try
- Feb 19th, 2011
Platform Dependency: If a compiled program requires any additional library(s) to make the original program run on any particular OS, is platform dependency. Example, to run an executable C or C++ prog...
Erumesh kumar
- Jan 15th, 2011
A program that run at any OS means, that is called platform independent and those programs run at any architecture of computer (hardware) are called machine independent and the phenomenon is platform and machine independency.
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Why Object is Super class in Java?
sampra
- Mar 6th, 2012
Answer Question Correct Answer prabhul Answered On : Nov 21st, 2011 Based on object oriented programming,the Object class, in the java.lang package, sits at the top of the class hierarchy tree. Ever...
prabhul
- Nov 21st, 2011
Based on object oriented programming,the Object class, in the java.lang package, sits at the top of the class hierarchy tree. Every class is a descendant, direct or indirect, of the Object class. Ever...
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Exception
When super class method throws exception then subclass also throws the same Exception, which will compile?
alin20_84
- Feb 14th, 2012
Here foo can skip adding throws NullPointerException because is an unchecked exception
class SupSub extends Super {
void foo()throws NullPointerException
{
System.out.println("SupSub");
}
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1) write a program that singleton objects returns two instances?
Give me answer
ksureshbabu
- Mar 5th, 2010
class Singletones implements Serializable{ /** * */ private static final long serialVersionUID = 6240073482570369797L; &...
Jagdeep Grewal
- Nov 8th, 2005
public class CSingleton { private static CSingleton inst= null;private static int count=0;protected CSingleton() { &n...
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Explain Garbage collection mechanism in Java
sampra
- Feb 20th, 2008
Like in c and c++ we have some mechanism to create the object and some mechnaishm to distroy the object .but in java we have mechanism to create the object but we dont have any mechanism t...
nuttyvarun
- Feb 20th, 2008
Garbage collection (GC) is a form of automatic memory management. The garbage collector, or just collector, attempts to reclaim garbage, or memory used by objects that will never be accessed or mutated again by the application.
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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. When i say stmt.executeQuery(). I am getting the records in my ResultSet. How it is possible?.. since there is no functionality insid the methods which is declared in Statement Interface. What is happning here?
An idea
vinaymudgil007
- Jun 3rd, 2008
Well the answer given by sarat is a very good one & explains the concept.....
sasi
- Jul 20th, 2006
hi.....for example..take SUN as example..they provides..only interfaces..that means..they give only NULL implementations..i.e.what is the returntype of the interface..what is the method & it...
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How to compare Stringbuffer objects?
Sarje
- Aug 19th, 2009
Since java.lang.StringBuffer class does not override equals(Object obj) method of the Object class then so you can not compare its objects directly. If you want to compare its objects then first conve...
rameshbabukm
- May 26th, 2007
The Known fact is the stringbuffer strore the data as charcter array, so when when we do a append on the stringbuffer object it inserts the chars into that array.Thats why we got method which can very the initial capacity of the same.hope it clarifies the doubt?
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How many JVM's we can run in a system?
phanibhushan.g
- Mar 12th, 2010
We can run as many JVMs as possible at the same time depending on the memory (RAM). Also the JVM instance can belong to any one of the java implementors like Sun JDK, JRockit etc parallely. For using ...
mytramesh
- Apr 7th, 2006
Hai Friends you have to remember one thing.The Jvm is one.Butwe can have mamy jvm instances. you open five commmand prompts and do java programs in all command prompts.All will execute.For ...
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What is collction framework?How it is working?Explain.
deepak
- Apr 15th, 2006
Collection is a java package that provides the facilities to work on a group of objects as a single unit.it contains intefaces and classes the provide this facility.
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What significance of protected Constructors?
jimmy514in
- Oct 27th, 2010
And , I thought constructors were NOT inherited..what probably protected means , is that private..you cannot directly call that constructor..I am unsure, if you can use protected and inherit..please clarify1
jimmy514in
- Oct 27th, 2010
What if I have a scenario?public class A{protected A(String str){//code block}public A(){this("name1");}public static void main(){new A();//now you can use the protected constructor..//or you can also use the static block to call the protected constructor..cant u?}}
Core Java Interview Questions
Ans