Polymorphism

Poly.java
1	public class Poly {
2
3	// An enum is just a set of possible values
4	public enum AttackType {
5	HEAT, EDGE, BLUNT, COLD, ACID, PUNCTURE
6	}
7
8	// This is an example of a static inner class
9	public static class Attack {
10	public final String name;
11	public final AttackType type;
12	public final int damage;
13	public Attack(String name,AttackType type,int damage) {
14	this.name = name;
15	this.type = type;
16	this.damage = damage;
17	}
18	}
19
20	// This is an example of an interface
21	public interface Monster {
22	public Attack getAttack();
23	public void takeDamage(Attack a);
24	}
25
26	// Orcs don't have an intrinsic attack, they
27	// have to carry a weapon.
28	public static class Orc implements Monster {
29	Attack weapon;
30	int life=20;
31
32	public void setWeapon(Attack weapon) {
33	this.weapon = weapon;
34	}
35	@Override
36	public Attack getAttack() {
37	return weapon;
38	}
39
40	@Override
41	public void takeDamage(Attack a) {
42	life -= a.damage;
43	if(life <=0 )
44	System.out.println("dead");
45	}
46	}
47
48	public static class Dragon implements Monster {
49	final Attack breath = new Attack("Breath",AttackType.HEAT,50);
50	int life = 100;
51
52	@Override
53	public Attack getAttack() { return breath; }
54
55	@Override
56	public void takeDamage(Attack a) {
57	if(a.type == AttackType.COLD)
58	life -= a.damage;
59	else
60	System.out.println("No damage, ha, ha, ha");
61	if(life <=0 )
62	System.out.println("dead");
63	}
64	}
65
66	// Polymorphism in action
67	public static void attack(Monster attacker,Monster defender) {
68	defender.takeDamage(attacker.getAttack());
69	}
70
71	public static void main(String[] args) {
72	Orc orc = new Orc();
73	Dragon dragon = new Dragon();
74	orc.setWeapon(new Attack("Sword",AttackType.EDGE,10));
75	attack(orc,dragon);
76	attack(dragon,orc);
77	}
78	}
$ javac Poly.java
$ java Poly No damage, ha, ha, ha dead