// Basic example concerning interface

// An interface is like a .h header in C++: It gives a specification but
// does not implement it.

interface athlete
{
    void score();
}

class basketballplayer implements athlete
{
    public void dribble() 
    { System.out.println("boing boing boing"); }

    public void score()
    {
	System.out.println("slam dunk");
    }
}

class footballplayer implements athlete
{
    public void tackle()
    { System.out.println("eat dirt!"); }

    public void score()
    {
	System.out.println("touchdown");
    }
}

class baseballplayer implements athlete
{
    public void pitch() 
    { System.out.println("zing"); }

    public void score()
    {
	System.out.println("home run");
    }
}

public class interfaces
{
    public static void main(String[] args)
    {
	athlete A;
	A = new footballplayer();
	// A.tackle(); -- gives compiler error (A's static type is athlete).
        // ((footballplayer)A).tackle(); -- this will work
	A.score();     // prints touchdown

	// The following line, may change A's run-time (dynamic type).
	// Obviously it cannot be predicated at compile-time.  At compile
	// time, the type of A is just "athlete" -the type it was declared as.
	if (Math.random()<0.5) A = new basketballplayer(); 
	A.score();    // prints touchdown or slam dunk (DYNAMIC Dispatch)

	// a polymorphic array of athletes:
	athlete[] T = new athlete[3];
	T[0] = new basketballplayer();
	T[1] = new baseballplayer();
	T[2] = new footballplayer();
	for (int i=0;i<T.length;i++) T[i].score(); // polymorphic code

    }//main
}