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 7627

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 4559

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; }

2339

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

2 4203

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 5134

what is data binding? give the example

TCS,

1 4840

what is deadlock in threads? with example

CTS, XOXO,

2 5624

Difference between abtsract & final

Nous,

1 4062

Difference between error and exception

Nous, TCS,

3 6060

Superclass of exception

Nous,

4 6672

Write POJO class as a key to hashmap???

2 12992

WAP to illustrate the use of interface

2 4185

Difference between Map & Hashmap

Mastek,

2 6523

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Un-Answered Questions { Core Java }

How large is a boolean?

1014

What are multiple inheritances?

1109

FOR EXAMPLE WE R HAVING TWO LIST ELEMENTS ..BOTH LISTS CONTAINS ID,NAME,PLACE ..I NEED TO COMPARE BOTH IDS IN TWO LISTS,IF ID'S R SAME MEANS WE HAVE ADD THE DETAILS(LIKE NAME,PLACE) TO MAP...HOW IS POSSIBLE ?CAN ANY ONE SUGGEST?

3476

What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?

1132

What are the four pillars of java?

1210

What is return used for in java?

1026

How is string immutable in java?

1037

What is the main function in java?

1069

What language is an assembler written in?

997

Can we sort set in java?

952

What are thread priorities and importance of thread priorities in java?

1139

What are the differences between the constructors and methods?

1116

Difference between class#getinstance() and new operator ?

1208

Explain about interthread communication and how it takes place in java?

1023

What are streams?

1123

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