一、运用多态解决宠物喂食问题

改变Master类的feed方法的参数列表

package com.hspedu.poly_;

public class Master {
    private String name;

    public Master(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    
    public void feed(Animal animal, Food food){
       System.out.println("主人" + name + "给"+ animal.getName() + "喂" + 
                food.getName());
    }

}

原理分析

1）animal的编译类型是Animal，可以指向(接收)Animal子类的对象

2）food的编译类型是Food，可以指向(接收)Food子类的对象

运行测试

在Poly01.java中测试，为了区分加~

package com.hspedu.poly_;

public class Poly01 {
    public static void main(String[] args) {
        Master master = new Master("小李");
        Dog spike = new Dog("Spike~");
        Bone bone = new Bone("大骨头~");
        
        master.feed(spike,bone);
        Cat tom = new Cat("Tom~");
        Fish fish = new Fish("鱼罐头~");
        master.feed(tom,fish);
    }
}

运行结果

分析

因为spike是Dog类的对象，Dog类是Animal的子类，Animal可以接收子类的对象的传参；bone传参的原理也是如此

增加宠物和食物种类

增加宠物Pig类继承Aniaml类，增加食物Rice类，继承Food类，别的都不需要，在Poly01中直接创建新对象然后调用feed方法即可，这就是多态的便利

Pig类

package com.hspedu.poly_;

public class Pig extends Animal{
    public Pig(String name) {
        super(name);
    }
}

Rice类

package com.hspedu.poly_;

public class Rice extends Food{
    public Rice(String name) {
        super(name);
    }
}

测试

package com.hspedu.poly_;

public class Poly01 {
    public static void main(String[] args) {
        Master master = new Master("小李");
        Dog spike = new Dog("Spike~");
        Bone bone = new Bone("大骨头~");
        master.feed(spike,bone);

        Cat tom = new Cat("Tom~");
        Fish fish = new Fish("鱼罐头~");
        System.out.println("===============");
        master.feed(tom,fish);

        Pig pig = new Pig("猪猪侠");
        Rice rice = new Rice("八宝饭");
        System.out.println("============");
        master.feed(pig,rice);

    }
}