JAVA INTERVIEW QUESTIONS AND ANSWERS

JAVA INTERVIEW QUESTIONS AND ANSWERS for 2021

This blog on JAVA Interview Questions is prepared to help you understand the basic concepts of Java programming for interview purposes. We have compiled a list of commonly asked Java Interview Questions and Answers that will help you prepare for the Basic Java interview questions that an interviewer might demand of you during your interview. In this list of fundamental Java interview questions, we have covered basic and advanced Java interview questions with comprehensive answers to help you clear the job interview.

The following list accommodates java interview questions for fresher’s as well as Java interview questions and answers for experienced programmers to support them and help them prepare for the interview. This comprehensive guide of interview questions for Java Programming will support you to crack your Job interview easily.

  • What is Java?
  • What are the features of Java?
  • How does Java enable high-performance?
  • Name the Java IDE’s
  • What do you mean by constructor?
  • What is meant by local variable and instance variable?
  • What is a class?
  • What is an object?
  • What are the OOPs concepts?
  • What is inheritance?
  • What is encapsulation?
  • What is polymorphism?
  • What is meant by method overriding?

JAVA INTERVIEW QUESTIONS AND ANSWERS 2021

Que.1- What is JAVA?

Answer: Java is a high-level programming language and it is platform-independent. Java is a collection of objects. It was developed by Sun Microsystems. There are a lot of applications, websites, and games that are developed by using Java.

Que.2- What are the features of JAVA?

Answer: Features of Java are as follows:

  • OOP concepts
    • Object-oriented
    • Inheritance
    • Encapsulation
    • Polymorphism
    • Abstraction
  • Platform independent: A single program works on different platforms without any restriction.
  • High Performance: Just in time compiler allow high performance in Java. Just in time converts the bytecode into machine language and then Java Virtual Machine starts the execution.
  • Multi-threaded: A flow of execution is called Multi-thread. Java virtual machine creates a thread which is called the main thread. The user can create multiple threads by increasing the thread class or by implementing the Runnable interface.

Que.3- How does Java enable high performance?

Answer: Java uses Just in Time compiler to permit high performance. It is used to turn the instructions into bytecodes.

Que.4- Name the Java IDE’s?

Answer: Eclipse and NetBeans are the integrated development environment of JAVA.

Que.5- What do you mean by Constructor?

Answer: A Constructor can be explained in detail with sign up for points:

  • Whenever a new object is created in a program a constructor gets called/invoked on corresponding to the class.
  • A constructor is a method which has the identical name as the class name.
  • If a user is excluded to create a constructor implicitly a default constructor will be created.
  • A constructor can be overloaded.
  • If the user has created a constructor with a parameter then he should create another constructor explicitly in the absence of a parameter.

Que.6-What is meant by the Local variable and the Instance variable?

Answer:

Local variables are defined in the method and scope of the variables that exist inside the method the masses.

Instance variable is interpret inside the class and outside the method and the scope of the variables exists throughout the class.

Que.7- What is a Class?

Answer: All Java codes are explain in a Class. It has variables and methods.

Variables are allot which define the state of a class.

Methods are the place where the exact business logic has to be ended. It contains a set of statements (or) instructions to please the particular requirement.

Que.8- What is an Object?

Answer: An occurence of a class is called an object. The object has state and behavior.

Whenever the java virtual machine reads the “new()” keyword then it will make an instance of that class.

Que.9-What are the OOPs concepts?

Answer: OOPs concepts include:

  • Inheritance
  • Encapsulation
  • Polymorphism
  • Abstraction
  • Interface

Que.10- What is Inheritance?

Answer: Inheritance technique one class can extend to another class. So that the codes can be restated from one class to another. The subsist class is known as the Super class whereas the extract class is known as a subclass.

Que.11-What is Encapsulation?

Answer: Purpose of Encapsulation:

  • Protects the code from others.
  • Code maintainability 

Que.12- What is Polymorphism?

Answer: Polymorphism means many forms.

A single object can refer to the superclass or subclass depending on the reference type which is called polymorphism.

Using the Manipulation recommendation type we can call the Addition class “add()” method. This ability is known as Polymorphism. Polymorphism is relevant for overriding and not for overloading.

Que.13- What is meant by Method Overriding?

Answer: Method overriding occur if the sub-class method satisfies the under conditions with the Superclass method:

  • Method name should be the same
  • The argument should be the same

Return type should also be the same.

This brings us to the end of the blog on Java Interview Questions. We hope that you were able to gain some knowledge from the same and are now better-equipped to attend an interview. Happy Learning!

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