Core Java Interview Questions, Answers for Freshers and Experienced asked in various Company Job Interviews

Core Java Interview Questions

Questions Answers Views Company eMail

The following program is Overloading or Overriding? public class PolymorphismEx { public int sampleMethod(int a) { return a; } public String sampleMethod(int a) { return "Is it Overloading or Overriding???"; } }

Ness Technologies, TCS,

4 7629

I Have a class abstract with one abstract method, so that method should override in the subclass, but i dont want to override, if i am not override what will happen? If compilation will occur then i dont want to give compilation error, then what we need to do??? See the sample program. public abstract class AbstractExample { public abstract void sampleMethod(); } public class AbstractExampleImple extends AbstractExample { }

Mphasis,

2 6044

is it mandatory to deaclare all variables public static fianl in interfaces?if i declare like in the below program, public interface A { public static final int I=0; int j=0; } in interface A,what is the difference between I,j?

2 4560

public class Test { public static void main(String[] args) { int countA = 0; int countB = 0; int countC = 0; int countD = 0; int countE = 0; int countF = 0; int countG = 0; int countH = 0; int countI = 0; int countJ = 0; int countK = 0; int countL = 0; int countM = 0; int countN = 0; int countO = 0; int countP = 0; int countQ = 0; int countR = 0; int countS = 0; int countT = 0; int countU = 0; int countV = 0; int countW = 0; int countX = 0; int countY = 0; int countZ = 0; } } Can anybody tell me any alternate solution(like loop or something) to automate this initialization process. Ex:- for(char chr='A';chr<='Z'; chr++) { (int) String "count"+chr = 0; }

2340

what is different between static and non static methods ,using example

2 4206

Which collection object is faster to retrieving the data and inserting the data into it.

Jamcracker, Virtusa,

2 8457

what is the difference b/w static and final methods?

1 5135

what is data binding? give the example

TCS,

1 4841

what is deadlock in threads? with example

CTS, XOXO,

2 5627

Difference between abtsract & final

Nous,

1 4064

Difference between error and exception

Nous, TCS,

3 6062

Superclass of exception

Nous,

4 6676

Write POJO class as a key to hashmap???

2 12993

WAP to illustrate the use of interface

2 4187

Difference between Map & Hashmap

Mastek,

2 6527

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Un-Answered Questions { Core Java }

What is complexity in java?

1048

What are the common uses of "this" keyword in java ?

1024

What are the advantages of arraylist over arrays?

1092

What is a parameter example?

977

What is the difference between yield() and sleep()?

1017

What do you understand by garbage collection in Java? Can it be forced to run?

986

What is a instance variable in java?

1046

What do you mean by light weight and heavy weight components?

1018

Is treeset sorted in java?

991

What is the different types of functions?

1057

Can a class have a static inner class?

1085

what r advatages of websphere? & how to deploy?

2196

Does java support multiple inheritance or not?

1106

Is null == null in java?

1108

Can an abstract class be a final class?

996

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