多态的使用

abstract class Animala{
    String name;
    abstract public void eat();
    
}
class Dog extends Animala{
    public void eat(){
        System.out.println("狗吃骨头");
    }
}
class Cat extends Animala{
    public void eat(){
        System.out.println("猫吃鱼");
    }
}
class MyAnimalList{
    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
    private int nextIndex = 0; //下标
    
    public void add(Animala a){
        if(nextIndex < animals.length){
            animals[nextIndex] = a;
            System.out.println("Animal add at "+ nextIndex );
            nextIndex++;
        }
    }
}
public class ThreeDuo {
    public static void main(String[] args){
        MyAnimalList list = new MyAnimalList(); //定义集合的对象
        Cat a = new Cat();
        Dog c = new Dog();
        list.add(a);
        list.add(c);
    }
}