一个理解多态的经典例子

/*多态的应用,构建父类的变量，指向子类的对象 * */ package com.guang;public class Duotai {/** * @param master */public static void main(String[] args) {/* * Animal an=new Cat(); an.cry(); an=new Dog(); an.cry(); */Master master = new Master();master.feed(new Dog(), new Bone());}}class Master {public void feed(Animal an, Food f) {an.eat();f.showname();}}class Food {String name;public void showname() {System.out.println();}}class Fish extends Food {public void showname() {System.out.println("给你鱼");}}class Bone extends Food {public void showname() {System.out.println("给你骨头");}}class Animal {String name;public void eat() {System.out.println("不知道吃什么");}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}int age;public void cry() {System.out.println("不知道怎么叫");}}class Cat extends Animal {public void cry() {System.out.println("猫猫叫");}public void eat() {System.out.println("猫爱吃鱼");}}class Dog extends Animal {public void cry() {System.out.println("汪汪叫");}public void eat() {System.out.println("狗爱吃骨头");}}