An interface in java is a blueprint of a class. It has static constants and abstract methods only. The interface in java is a mechanism to achieve fully abstraction. There can be only abstract methods in the java interface not method body. It is used to achieve fully abstraction and multiple inheritance in Java.
There are mainly three reasons to use interface. They are given below:-
1. It is used to achieve fully abstraction.
2. By interface, we can support the functionality of multiple
inheritance.
3. It can be used to achieve loose coupling.
The java compiler adds public and abstract keywords before the interface method and public, static and final keywords before data members. In other words, Interface fields are public, static and final by default, and methods are public and abstract.
