ניתוח פולימורפיזם במחלקות יונקים

1public class Mammal {
2    protected int weight;
3    public Mammal(int w) {
4        weight = w;
5    }
6    public int getWeight() {
7        return weight;
8    }
9    public boolean isSame(Mammal other) {
10        System.out.println("In Mammal");
11        return (this == other);
12    }
13}
14public class Antelope extends Mammal {
15    public Antelope(int w) { super(w); }
16    public boolean isSame(Antelope other) {
17        System.out.println("In Antelope");
18        return ((other != null) && (this.weight == other.weight));
19    }
20}
21public class Beaver extends Mammal {
22    public Beaver(int w) { super(w); }
23    public boolean isSame(Mammal other) {
24        System.out.println("In Beaver");
25        return ((other != null) && (other instanceof Beaver) && (this.weight == ((Beaver)other).weight));
26    }
27}
28
29public class Program {
30    public static void main(String[] args) {
31        Antelope a1 = new Antelope(10);
32        Object a2 = new Antelope(10);
33        Beaver b1 = new Beaver(10);
34        Mammal b2 = new Beaver(10);
35        *******
36    }
37}