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

Core Java Interview Questions

Questions Answers Views Company eMail

whether java is fully object oriented language or partially object oriented language

Infosys, ME, SMK,

4 8449

while creating thread why we extend thread class

2 4969

How HashMap implemented in java? how it internally works when values are added or searched from hashMap?What is the difference betweenthe implementation of hashmap and Linked Hashmap?

IBM,

3 10663

what is mean by synchronization?

BOB Technologies, GCPL,

3 6509

what is mean by thread lock?

Infosys, TCS,

2 6452

I declared main() method as private. But it still running and displaying the output. Please Answer it . Code Snippet as Below: import java.io.*; class over { private static void main(String[] args) { int high = Integer.MAX_VALUE; int overflow = high + 1; int low = Integer.MIN_VALUE; int underflow = low - 1; System.out.println(high + "\n" +overflow +"\n"+ low +"\n"+underflow); //System.out.println(overflow); //System.out.println(low); //System.out.println(underflow); } }

Cap Gemini,

4 7429

Hi Every One I Have Small Doubt Please answer This???????????????????????????? I Want to use AbstractList class methods(java.util.AbstractList) My Program is import java.util.*; class DemoOne extends AbstractList { public static void main(String[] args) { AbstractList a=new DemoOne();//This One is Correct?? DemoOne a1=new DemoOne();//This One is Correct?? Both Are Not Working System.out.println("Hello World!"+a); System.out.println("Hello World!"+a1); } } Error IS: DemoOne.java:2: DemoOne is not abstract and does not override abstract method get(int) in java.util.AbstractList class DemoOne extends AbstractList AnyOne can Please Provide The Solution????????????????????????? Plzzzzzzz

3 4819

how system.out.println() works?

2 5124

In Inheritance if we are implementing Multi level inheritance and all class having same name of variable and now i want to access each class variable and how it is possible?

2 5049

What is the alternate of 'Inheritance' ?

CybAge, HCL,

4 13925

explain how many oops concepts available in java with realtime scenarios?

TCS,

1 14240

int a=1,b=10; System.out.println(a+b--);

HCL,

12 17189

1) Find the Merge point of two linked lists. 2) Swap two bits of integer. 3) Reverse individual words of the sentence. 4) Reverse string without using temp string.

HCL,

2 6575

what is object slice?

2076

why did you choose your career in IT?

LIC,

1 3773

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Un-Answered Questions { Core Java }

What is the difference between hashmap and hashtable in java?

1113

Is arraylist zero based?

1061

What is the difference between procedural and object-oriented programs?

968

Is an object null?

971

How do you check if a number is a perfect square?

992

Explain the hierarchy of java exception classes?

1094

What do you mean by aggregation?

1313

What is nextline method in java?

1025

Where is singleton pattern used?

991

What is the console in java?

1148

how many types of Inheritance?

1166

What is a method vs function?

1033

Is alive and join method in java?

1163

What is the difference between arraylist and hashset in java?

1137

Can a lock be acquired on a class in java programming?

991

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