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 7630

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 6045

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 4561

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; }

2341

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

2 4208

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

Jamcracker, Virtusa,

2 8461

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 6063

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 6528

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Un-Answered Questions { Core Java }

What are invisible components?.

2147

What is array initialization in java?

1101

Define max and min heap, also the search time of heap.

1028

Can we have two methods in a class with the same name?

1053

What is package private scope in java?

949

How can we avoid including a header more than once?

1040

What is ph and buffers?

1006

How do you create a null object?

1088

What is the use of private static?

1051

What is run time allocation?

1026

What is java reflection?

986

How many threads can java run?

1115

Can private class be extended java?

1030

Why do we use bufferedreader?

1010

Explain which of the following methods releases the lock when yield(), join(),sleep(),wait(),notify(), notifyall() methods are executed?

1119

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