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 7768

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 6148

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 4652

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; }

2374

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

2 4321

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

Jamcracker, Virtusa,

2 8549

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

1 5235

what is data binding? give the example

TCS,

1 4932

what is deadlock in threads? with example

CTS, XOXO,

2 5732

Difference between abtsract & final

Nous,

1 4142

Difference between error and exception

Nous, TCS,

3 6165

Superclass of exception

Nous,

4 6819

Write POJO class as a key to hashmap???

2 13117

WAP to illustrate the use of interface

2 4289

Difference between Map & Hashmap

Mastek,

2 6637

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Un-Answered Questions { Core Java }

What is mnemonic code?

1078

What is logical variable?

1043

What is static keyword in java?

1057

What is size () in java?

1150

What does java ide mean?

1211

What is a boolean used for?

1162

What is the simpletimezone class in java programming?

1169

What is nextint java?

1133

What is final keyword in java?

1069

Why is an interface be able to extend more than one interface but a class can’t extend more than one class?

1219

How do you convert bytes to character in java?

1053

How can you set an applet’s height and width as a percentage?

976

What interface is extended by awt event listeners?

1103

What is the meaning of 3 dots in java?

1209

How does thread synchronization occurs inside a monitor?

1181

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