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 7421

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 5942

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 4442

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; }

2288

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

2 4054

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

Jamcracker, Virtusa,

2 8325

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

1 4977

what is data binding? give the example

TCS,

1 4746

what is deadlock in threads? with example

CTS, XOXO,

2 5500

Difference between abtsract & final

Nous,

1 3972

Difference between error and exception

Nous, TCS,

3 5910

Superclass of exception

Nous,

4 6476

Write POJO class as a key to hashmap???

2 12840

WAP to illustrate the use of interface

2 4076

Difference between Map & Hashmap

Mastek,

2 6371

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Un-Answered Questions { Core Java }

Why is stringbuffer called mutable?

936

What is data type modifier?

887

Can we override compareto method?

900

Can we create an object if a class doesn't have any constructor ( not even the default provided by constructor ) ?

1027

When should you make a function static?

930

Why do people says “java is robust”?

957

How many types of exception can occur in a java program?

929

Explain some best practices you would apply while using collection in java?

983

What is anagram number?

883

What does 3 dots mean in java?

925

What is gc()?

980

What is the Scope of Static Variable?

1165

Explain java coding standards for methods?

984

Is multiple inheritance supported by java?

925

What are the default and parameterized constructors?

1018

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