Java - Interface

Interface:-

        It is like as abstract class but one exception that in which all the methods cannot have body.

        All the methods of an interface are public and abstract by default.

        All the methods of an interface should be defined(implemented) by its derived class.

        All the variables declared with in an interface are public,static and final by default.

        Since interface can not be instantiated,it should have atleast one derived class.

        To achieve "pure dynamic polymorphism".

        A class can inherit more than one interfaces using the keyword "implements".

        An interface can inherit another interface using the keyword "extends".

syntax to define an interface:-

<specifier> interface <interfacename>

   {

        methods decl;

        constant fields decl&init;

   }

<specifier>class childclassname implements interfacename1,interfacename2

{

        interface method definition

        class own method definition

}