老师来康康

public abstract class Animal {

//按任务要求实现该类

   private String name;

   //getter/setter方法

public String getName() {

return name;

}

public Animal() {

super();

// TODO Auto-generated constructor stub

}

public Animal(String name) {

super();

this.name = name;

}

public void setName(String name) {

this.name = name;

}

public abstract void play();

}

==========================================

package test20200630;

public class Dog extends Animal{

public Dog() {

super();

// TODO Auto-generated constructor stub

}

public Dog(String name) {

this.setName(name);

// TODO Auto-generated constructor stub

}

@Override

public void play() {

System.out.println("小狗"+this.getName()+"在做游戏！");

}

}

============================================

public class Cat extends Animal{

public Cat() {

// TODO Auto-generated constructor stub

}

public Cat(String name) {

this.setName(name);

// TODO Auto-generated constructor stub

}

@Override

public void play() {

// TODO Auto-generated method stub

System.out.println("小猫"+this.getName()+"在做游戏！");

}

}

=========================================

import java.util.List;

public class AnimalPlay {

public void animalPlay(List<? extends Animal> list) {

for(Animal a:list) {

a.play();

}

}

}

===========================================

import java.util.ArrayList;

import java.util.List;

public class Test {

public static void main(String[] args) {

// 定义List并添加Dog类对象

List<Dog> dog=new ArrayList<Dog>();

Dog d1=new Dog("巴迪");

Dog d2=new Dog("豆豆");

dog.add(d1);

dog.add(d2);

// 定义List并添加Cat类对象

List<Cat> cat=new ArrayList<Cat>();

Cat c1=new Cat("花花");

Cat c2=new Cat("凡凡");

cat.add(c1);

cat.add(c2);

// 使用AnimalPlay类的方法，按照演示效果输出内容

AnimalPlay ap=new AnimalPlay();

ap.animalPlay(dog);

ap.animalPlay(cat);

}

}

老师我这代码在eclipse里运行会跳这个提示，请问是啥原因啊？