Java and Collection Interfaces

Interface : Types of Interfaces

Interface ,simply say something to a media by using another media. For example TV Remote is an interface because it is medium for giving the command to a TV for changing the channels or to ON/OFF the TV.

Interface is nothing , the collection of methods with empty implementations and constants variables .All the variables declarations are static and final. All the methods in an interface are "public and abstract" by default. Interfaces are abstract in nature so they can not be directly instantiated.For defining the methods of an interface use the keyword "Implements ".Interfaces are just like the abstract classes but the major difference between these two is that interface contains all the methods abstract while abstract classes must have at least one abstract method.

Interface Definition

access specifier interface(keyword) interfacename{

constant variable declarations ;

abstract methods declarations ;

}

For Example

interface Firstinterface // use keyword interface & interfacename
{
int a=100; // by default contant variable

}
interface Secondinterface extends Firstinterface // for accessing the functionality of Firstinterface use extends keyword
{
int b=200;
int sum = a+b;
void Display();
}
class Interfaceclass implements Secondinterface // for using the functionality of Firstinterface & Secondinterface use the keyword implements
{
public void Display()
{
System.out.println(sum);
}
public static void main(String[] args)
{
Interfaceclass temp = new Interfaceclass();

temp.Display();
}
}

In Java there is no types of the interfaces . In collection we have three interfaces such as :-

(1) List interface

(2) Set interface

(3) HashMap interface


Neetu ;)