interface Electronics

{ void cost(); // Interface consist pure abstract methods , interface by default is abstract and public method.

void battery();

}

abstract class Mobile implements Electronics

{ void simslot()

{ System.out.println( "Every mobile has slimslot");

}}

class Iphone extends Mobile

{ public void cost() // public keyword is mandatory here beacuse cost and battery methods of interface are public.

{System.out.println( "This mobile is 1000");}

public void battery() // Also, methods of the interface must be overridden

{ System.out.println( "This battery is small size");}

}

class Samsung extends Mobile

{ public void cost()

{System.out.println( "This mobile is 9000");}

public void battery()

{ System.out.println( "This battery is big in size");}

}

abstract class Laptop implements Electronics

{ void InbuiltSoftware()

{ System.out.println( "Every laptop has Inbuilt software");

}}

class Dell extends Laptop

{ public void cost() // public keyword is mandatory here beacuse cost and battery methods of interface are public.

{System.out.println( "This laptop is 8000");}

public void battery() // Also, methods of the interface must be overridden

{ System.out.println( "This battery is inside ");}

}

class Mac extends Laptop

{ public void cost()

{System.out.println( "This laptop is 5000");}

public void battery()

{ System.out.println( "This battery has good life time");}

}

class UsingInterface

{ public static void main(String ar[])

{ Mobile x= new Samsung(); // Using upcasting

x.cost();

x.battery();

x.simslot();

x= new Iphone();

x.cost();

x.battery();

x.simslot();

Laptop y= new Dell();

y.cost();

y.battery();

y.InbuiltSoftware();

y= new Mac();

y.cost();

y.battery();

y.InbuiltSoftware();}}