Interface in Java

Interface

Java doesn’t support multiple inheritance (means you can’t extends more than one class to a single class e.g.   class derived extends base1,base2) .

But there is often requirement of program to inherit a class from more than one class.

Then Interface comes into picture. And as we “extends” the class similarly we “implements” interface.

Interface: --- it is from of collection of abstract method (methods without definition). Keyword interface is used to declare an interface.

NOTE :-- whenever you implements a interface in any class the function which is declared  in interface must be overrided in derived class.

NOTE :-- if you are implementing interface and extending any class simultaneously make sure extends is before implements.

Example:--

interface base1

{

                public void show();

}

interface base2

{

                public void disp();

               

}

class normal

{

                void display()

                {

                                System.out.println("this is normal class");

                }

}

class derived extends normal implements base1,base2

{

                public void show() //overriding show()

                {

                                System.out.println("this is base1 interface method");

                }

                public void disp() //overriding disp()

                {

                                System.out.println("this is base2 interface method");

                }

}

public class abc

{

                public static void main(String as[])

                {

                                               

                                derived d=new derived();

                                d.show();

                                d.disp();

                                d.display();

                }

}