Java Operators

Java Control Statements

Object Oriented Programming

Java Built-in Classes

Java File Handling

Java Error & Exceptions

Java Multithreading

Java Synchronization

Java Networking

Java Collections

Java Interfaces

Java Data Structures

Java Collections Algorithms

Advanced Java

Java Miscellaneous

Java APIs & Frameworks

Java Class References

Java Useful Resources

Java Online Quiz

Following quiz provides Multiple Choice Questions (MCQs) related to Core Java. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.

Q 1 - Static functions can be accessed using null reference.

A - True

B - False

Answer : A

Explaination

True, Static functions can be accessed via class name or via null reference.

Q 2 - Can we have two public classes in one java file?

A - True

B - False

Answer : B

Explaination

No, a java file can contain only one public class.

Q 3 - What is the default value of char variable?

Answer : A

Explaination

char variable has default value of '\u0000' if defined as an instance/static variable.

Q 4 - Which of the following is true about public access modifier?

A - Variables, methods and constructors which are declared public can be accessed by any class.

B - Variables, methods and constructors which are declared public can be accessed by any class lying in same package.

C - Variables, methods and constructors which are declared public in the superclass can be accessed only by its child class.

D - None of the above.

Answer : A

Explaination

Public access modifier is used to make variables, methods and constructors accessible to any class.

Q 5 - What is Abstraction?

A - Abstraction is a technique to define different methods of same type.

B - Abstraction is the ability of an object to take on many forms.

C - It refers to the ability to make a class abstract in OOP.

D - None of the above.

Answer : C

Explaination

It refers to the ability to make a class abstract in OOP. It helps to reduce the complexity and also improves the maintainability of the system.

Q 6 - What is static block?

A - It is used to create syncronized code.

B - There is no such block.

C - It is used to initialize the static data member., It is excuted before main method at the time of class loading.

D - None of the above.

Answer : C

Explaination

static block is used to initialize the static data member.It is executed before main method at the time of loading of a class.

Q 7 - What is true about a final class?

A - class declard final is a final class.

B - Final classes are created so the methods implemented by that class cannot be overridden.

C - It can't be inherited.

D - All of the above.

Answer : D

Explaination

Final classes are created so the methods implemented by that class cannot be overridden. It can't be inherited. These classes are declared final.

Q 8 - What invokes a thread's run() method?

A - JVM invokes the thread's run() method when the thread is initially executed.

B - Main application running the thread.

C - start() method of the thread class.

D - None of the above.

Answer : A

Explaination

After a thread is started, via its start() method of the Thread class, the JVM invokes the thread's run() method when the thread is initially executed.

Q 9 - Can a top level class be private or protected?

A - True.

B - False.

Answer : B

Explaination

No, a top level class can not be private or protected. It can have either "public" or no modifier.

Q 10 - Which of the following is Faster, StringBuilder or StringBuffer?

A - StringBuilder

B - StringBuffer

C - Both of the above.

D - none of the above.

Answer : A

Explaination

StringBuilder is faster than StringBuffer.

java_questions_answers.htm