java学习多态的好处和弊端

多态的好处：提高了程序的扩展性

    具体体现：定义方法的时候，使用父类型作为参数，将来在使用的时候，使用具体的子类型参与操作。

多态的弊端：不能使用子类的特有功能

package com.ithema_37;
/*
   测试类
 */
public class AnimalDemo {
    public static void main(String[] args) {
        //创建动物操作类的对象，调用方法
        AnimalOperator aO = new AnimalOperator();

        Cat c = new Cat();
        aO.useAnimal(c);

        Dog d = new Dog();
        aO.useAnimal(d);

        Pig p = new Pig();
        aO.useAnimal(p);
    }
}

package com.ithema_37;

public class Animal {

    public void eat(){
        System.out.println("动物吃东西");
    }
}

package com.ithema_37;
/*
  动物操作类
 */
public class AnimalOperator {
    /*

    public void useAnimal(Cat c){ //Cat c = new Cat();
        c.eat();
    }
    public void useAnimal(Dog d) { //Dog d = new Dog();
        d.eat();
    }
    */
    public  void useAnimal(Animal a){
        //Animal a = new Cat();
        //Animal a = new Dog();
        a.eat();
//        a.lookDoor();
    }
}

package com.ithema_37;


public class Cat extends Animal{
    @Override
    public void eat() {
        System.out.println("猫吃鱼");
    }
}

package com.ithema_37;

public class Dog extends Animal{

    @Override
    public void eat() {
        System.out.println("狗吃骨头");
    }
    public void lookDoor(){
        System.out.println("狗看大门");
    }
}

package com.ithema_37;

public class Pig extends Animal{
    @Override
    public void eat() {
        System.out.println("猪爱吃饲料");
    }
}