Interface
An interface defines a protocol of behavior
that can be implemented by any class anywhere in the class hierarchy. An
interface defines a set of methods but does not implement them. A class
that implements the interface agrees to implement all the methods
defined in the interface, thereby agreeing to certain behavior.
Differences interface and abstract class:
An interface cannot implement any methods, whereas an abstract
class can.
A class can implement many interfaces but can have only one
superclass.
An interface is not part of the class hierarchy. Unrelated
classes can implement the same interface.
The Java Platform
Interface
