Java Interview Questions

Q #1) What is JAVA?

Ans: Java is a high-level programming language and 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 using Java.

Q #2) What are the features in JAVA?

Ans: Features of Java:

• Oops concepts
  • Object-oriented
  • Inheritance
  • Encapsulation
  • Polymorphism
  • Abstraction

• Platform independent: A single program works on different platforms without any modification.
• High Performance: JIT (Just In Time compiler) enables high performance in Java. JIT converts the bytecode into machine language and then JVM starts the execution.
• Multi-threaded: A flow of execution is known as a Thread. JVM creates a thread which is called main thread. The user can create multiple threads by extending the thread class or by implementing Runnable interface.

Q #3) How does Java enable high performance?

Ans: Java uses Just In Time compiler to enable high performance. JIT is used to convert the instructions into bytecodes.

Q #4) What are the Java IDE’s?

Ans: Eclipse and NetBeans are the IDE's of JAVA.

Q #5) What do you mean by Constructor?

Ans: The points given below explain what a Constructor is in detail:

• When a new object is created in a program a constructor gets invoked corresponding to the class.
• The constructor is a method which has the same name as class name.
• If a user doesn’t create a constructor implicitly a default constructor will be created.
• The constructor can be overloaded.
• If the user created a constructor with a parameter then he should create another constructor explicitly without a parameter.