public class CovariantTest {

    public static void main(String args[]) {
	//FIRST WE SET UP ALL THE OBJECTS, NOTICE THE LAST IS SPECIAL
	A tempA=new A();
	B tempB=new B();
	X tempX=new X();
	Y tempY=new Y();
	X tempZ=new Y();  //Dynamic dispatch
	
	System.out.println("Test dispatch on B with one variable.");
	System.out.println("Last two should be the same if dynamic dispatch works.");
	tempB.test(tempX);
	tempB.test(tempY);
	tempB.test(tempZ);

	System.out.println("Test dispatch on B with two variables.");
	System.out.println("The second should be identical to the first if dynamic dispatch works.");
	tempB.test2(tempX, tempX);
	tempB.test2(tempX, tempX);
	System.out.println("---");
	tempB.test2(tempX, tempY);
	tempB.test2(tempX, tempZ);
	System.out.println("---");
	tempB.test2(tempY, tempX);
	tempB.test2(tempZ, tempX);
	System.out.println("---");
	tempB.test2(tempY, tempY);
	tempB.test2(tempZ, tempZ);
    }//main
}//CovariantTest


class A{
	public void test(X x){
		System.out.println("A.X run");
	}//test
	
	public void test2(X a, X b){
		System.out.println("A.XX run");
	}//test2		
}//A

class B extends A{
	public void test(Y x){
		System.out.println("B.Y run");
	}//test

	public void test2(X a, Y b){
		System.out.println("B.XY run");
	}//test2		

	public void test2(Y a, X b){
		System.out.println("B.YX run");
	}//test2		

	public void test2(Y a, Y b){
		System.out.println("B.YY run");
	}//test2		


}//B

class X{
}//X

class Y extends X{
}//Y