Data Structures Homework 1, Spring 2000, 40 Points

public class A extends Object {
    A() { /* null constructor */ }
    public void printMe() { System.out.println("I'm first."); }
}
public class B extends A {
    B() { /* null constructor */ }
    public void printMe() { System.out.println("I'm second."); }
}
public class C extends B {
    C() { /* null constructor */ }
    public void printMe() { System.out.println("I'm third."); }
}
public class D extends C {
    D() { /* null constructor */ }
    public void printMe() { System.out.println("Rank doesn't matter, man."); }
    public static void main(String[] args) {
        B bill = new C();
        A george = new A();
        Object obj = new D();
        Object interim = new B();
        bill.printMe();
        george.printMe();
        ((C) obj).printMe();
        obj = bill;
        ((A) obj).printMe();
        obj = interim;
        ((B) obj).printMe();
    }
}