1 abstract class Animala{
2 String name;
3 abstract public void eat();
4
5 }
6 class Dog extends Animala{
7 public void eat(){
8 System.out.println("狗吃骨头");
9 }
10 }
11 class Cat extends Animala{
12 public void eat(){
13 System.out.println("猫吃鱼");
14 }
15 }
16 class MyAnimalList{
17 private Animala[] animals = new Animala[5]; //初始化数组，即这个数组里可以放5个Animala类型的类的对象
18 private int nextIndex = 0; //下标
19
20 public void add(Animala a){
21 if(nextIndex < animals.length){
22 animals[nextIndex] = a;
23 System.out.println("Animal add at "+ nextIndex );
24 nextIndex++;
25 }
26 }
27 }
28 public class ThreeDuo {
29 public static void main(String[] args){
30 MyAnimalList list = new MyAnimalList(); //定义集合的对象
31 Cat a = new Cat();
32 Dog c = new Dog();
33 list.add(a);
34 list.add(c);
35 }
36 }
