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 - What is the size of int variable?

Answer : C

Explaination

The int data type is represented by 32-bit signed two's complement integer,

Minimum value: -231

Maximum value: 231-1

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

Answer : A

Explaination

int variable has default value of 0 if defined as an instance/static variable.

Q 4 - What is polymorphism?

A - Polymorphism is a technique to define different objects of same type.

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

C - Polymorphism is a technique to define different methods of same type.

D - None of the above.

Answer : B

Explaination

Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object.

Q 5 - What is local variable?

A - Variables defined inside methods, constructors or blocks are called local variables.

B - Variables defined outside methods, constructors or blocks are called local variables.

C - Static variables defined outside methods, constructors or blocks are called local variables.

D - None of the above.

Answer : A

Explaination

Variables defined inside methods, constructors or blocks are called local variables. The variable will be declared and initialized within the method and it will be destroyed when the method has completed.

Q 6 - What is an applet?

A - An applet is a Java program that runs in a Web browser.

B - Applet is a standalone java program.

C - Applet is a tool.

D - Applet is a run time environment.

Answer : A

Explaination

An applet is a Java program that runs in a Web browser.

Q 7 - Dynamic binding uses which information for binding?

A - type.

B - object.

C - Both of the above.

D - None of the above.

Answer : B

Explaination

Dynamic binding uses object information for binding.

Q 8 - What happens when thread's sleep() method is called?

A - Thread returns to the ready state.

B - Thread returns to the waiting state.

C - Thread starts running.

D - None of the above.

Answer : B

Explaination

When a task invokes its sleep() method, it returns to the waiting state.

Q 9 - What is runtime polymorphism?

A - Runtime polymorphism is a process in which a call to an overridden method is resolved at runtime rather than at compile-time.

B - Runtime polymorphism is a process in which a call to an overloaded method is resolved at runtime rather than at compile-time.

C - Both of the above.

D - None of the above.

Answer : A

Explaination

Runtime polymorphism or dynamic method dispatch is a process in which a call to an overridden method is resolved at runtime rather than at compile-time. In this process, an overridden method is called through the reference variable of a superclass.

Q 10 - What is currentThread()?

A - It is a Thread public static method used to obtain a reference to the current thread.

B - It is a thread's instance method used to get thread count.

C - It is a object's public static method used obtain a reference to the current thread.

D - It is a object's instance method used to get thread count.

Answer : A

Explaination

currentThread() is a public static method of Thread class used to obtain a reference to the current thread.

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