# CoreJavaInterviewQuestion
Core Java Interview Question


#### Q1 What is JAVA? 
     Java is a high-level programming language and is platform-independent.It 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.

#### Q2  What are the features of JAVA? 
  #### 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 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 the main thread. The user can create multiple threads by extending the thread                        
                       class or by implementing the Runnable interface.

#### Q3  How does Java enable high performance?
         Java uses Just In Time compiler to enable high performance. It is used to convert the instructions into bytecodes.
 
#### Q4  What do you mean by Constructor?
#### Constructor can be explained in detail with enlisted points:

  * 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 the 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.

#### Q5  What is meant by the Local variable and the Instance variable?
* Local variables* are defined in the method and scope of the variables that exist inside the method itself.
* Instance variable* is defined inside the class and outside the method and the scope of the variables exists throughout the class.