about interface

                                                               INTERFACE

 ABOUT Interface:

Interface in java is core part of Java programming language and one of the ways to achieve abstraction in Java along with abstract class. Even though interface is fundamental object oriented concept. Many Java programmers thinks Interface in Java as advanced concept and refrain using interface from early in programming career. At very basic level interface in java is a keyword but same time it is an object oriented term to define contracts and abstraction, this contract is followed by any implementation of Interface in Java. Since multiple inheritance is not allowed in Java, interface is only way to implement multiple inheritance at Type level.

ü  Interface in java is declared using keyword interface and it represent a Type like any Class in Java. a reference variable of type interface can point to any implementation of that interface in Java.

ü  All methods declared inside Java Interfaces are implicitly public and abstract, even if you don't use public or abstract keyword. you can not define any concrete method in interface. That's why interface is used to define contracts in terms of variables and methods and you can rely on its implementation for performing job.

ü  Interface contains the data members and the methods prototypes.

ü  When we create a class using the Interface we have to make use of the implements keyword.

The general form of the interface is ,

                        interface interfacename

                        {

                                    datatype1 item1=value1;

                                                :                                   :

                                    datatype1 itemn=valuen;

                                    returntype1 methodname1(argument list1);

                                                :                                   :

                                    returntypen methodnamen(argument listn);

                        }