JAVA_多态

多态的存在有三个必要条件：

1.要有继承

2.要有重写

3.父类引用指向子类对象

 1 class Animal {
 2   private String name;
 3   Animal(String name) {this.name = name;}
 4
 5   public void enjoy(){
 6     System.out.println("叫声......");
 7   }
 8 }
 9
10 class Cat extends Animal {
11   private String eyesColor;
12   Cat(String n,String c) {super(n); eyesColor = c;}
13
14   public void enjoy() {
15     System.out.println("猫叫声......");
16   }
17 }
18
19 class Dog extends Animal {
20   private String furColor;
21   Dog(String n,String c) {super(n); furColor = c;}
22
23   public void enjoy() {
24     System.out.println("狗叫声......");
25   }
26 }
27
28 class Bird extends Animal {
29      Bird() {
30           super("bird");
31      }
32      public void enjoy() {
33     System.out.println("鸟叫声......");
34   }
35 }
36
37 class Lady {
38     private String name;
39     private Animal pet;
40     Lady(String name,Animal pet) {
41         this.name = name; this.pet = pet;
42     }
43     public void myPetEnjoy(){pet.enjoy();}
44 }
45
46 public class Test {
47     public static void main(String args[]){
48         Cat c = new Cat("catname","blue");
49         Dog d = new Dog("dogname","black");
50         Bird b = new Bird();
51         Lady l1 = new Lady("l1",c);
52         Lady l2 = new Lady("l2",d);
53         Lady l3 = new Lady("l3",b);
54         l1.myPetEnjoy();
55         l2.myPetEnjoy();
56         l3.myPetEnjoy();
57     }
58 }