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 8476

while creating thread why we extend thread class

2 4980

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 10681

what is mean by synchronization?

BOB Technologies, GCPL,

3 6530

what is mean by thread lock?

Infosys, TCS,

2 6466

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 7441

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 4835

how system.out.println() works?

2 5137

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 5056

What is the alternate of 'Inheritance' ?

CybAge, HCL,

4 13953

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

TCS,

1 14249

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

HCL,

12 17256

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 6588

what is object slice?

2084

why did you choose your career in IT?

LIC,

1 3776

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Un-Answered Questions { Core Java }

What is the final field modifier?

974

Why is it important to initialize a variable?

993

What is runtime polymorphism or dynamic method dispatch?

1008

What is linked hashset and its features?

1060

Java Compiler is stored in JDK, JRE or JVM?

1522

Is empty .java file name a valid source file name?

1122

What is Garbage Collection in Java

1084

How do you write methodology?

986

How to overcome the exception object reference not set to an instance of object?

1153

Suppose if we have variable ' I ' in run method, if I can create one or more thread each thread will occupy a separate copy or same variable will be shared?

1055

Why multiple inheritance is not supported by java?

979

Name few "optional" classes introduced with java 8 ?

1135

What is garbage collector?

1082

What is collection class in java?

1007

How do you identify if jvm is 32-bit or 64-bit from java program?

968

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