Interface in Java

Hello Friends today we learn about Interface in Java
An interface is a reference type in Java, it is similar to class, it is a collection of abstract methods. A class implements an interface, thereby inheriting the abstract methods of the interface.

Interface is similar to a class:

An interface can contain any number of methods.

An interface is written in a file with a .java extension, with the name of the interface matching the name of the file.
The byte code of an interface appears in a .class file.
Interfaces appear in packages, and their corresponding bytecode file must be in a directory structure that matches the package name.

How Interface is different from a class:

You cannot instantiate an interface.
An interface does not contain any constructors.
All of the methods in an interface are abstract.
An interface cannot contain instance fields. The only fields that can appear in an interface must be declared both static and final.
An interface is not extended by a class; it is implemented by a class.
An interface can extend multiple interfaces.

Why use Interface ?

It is used to achieve fully abstraction.
By interface, we can support the functionality of multiple inheritance.
It can be used to achieve loose coupling.

Example of Java interface

interface printable{
void print();
}

class A6 implements printable{
public void print(){System.out.println("Hello");}

public static void main(String args[]){
A6 obj = new A6();
obj.print();
}
}