java 多态执行顺序

1.接口实现多态
interface A {
	public String sayHello();
}

class B implements A
{
	public String sayHello()
	{
		return "Hello B";
	}
}

class C implements A
{
	public String sayHello()
	{
		return "Hello C";
	}
}
public class test{
	public static void main(String args[]){
		A a1 = new B();
		A a2 = new C();
		System.out.println(a1.sayHello());
		
		System.out.println(a2.sayHello());
	}	
}
2.继承实现多态
public class A {


    public String show(D obj) {
        return ("A and D");
    }

    
    public String show(A obj) {
        return ("A and A");
    }
}
public class B extends A{






    public String show(B obj)


    {


        return "B and B";


    }


    


    public String show(A obj)


    {


        return "B and A";


    }


}


public class C extends B{
	public String show(C obj)


    {


        return "C and C";


    }


    


    public String show(A obj)


    {


        return "C and A";


    }
}


public class D extends B {
	public String show(D obj)


    {


        return "D and D";


    }


    


    public String show(A obj)


    {


        return "D and A";


    }
}


public class PolymorphismTest {


	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		A a1 = new A();
        A a2 = new B();
        B b = new B();
        C c = new C(); 
        D d = new D(); 
        System.out.println("a1.show(b) " + a1.show(b));
        System.out.println("a1.show(c) " + a1.show(c));
        System.out.println("a1.show(d) " + a1.show(d));
        System.out.println("a2.show(b) " + a2.show(b));
        System.out.println("a2.show(c) " + a2.show(c));
        System.out.println("a2.show(d) " + a2.show(d));
        System.out.println("b.show(b) " + b.show(b));
        System.out.println("b.show(c) " + b.show(c));
        System.out.println("b.show(d) " + b.show(d));
	}


}