多态应用-打印商品价格案例

1 package com.szxs.goods;
2 /**
3  * 父类：商品类
4  * @author 
5  *
6  */
7 public abstract class Goods {
8     public abstract void printPrice();
9 }

 1 package com.szxs.goods;
 2 
 3 //食品类
 4 public class Foods extends Goods {
 5 
 6     public void printPrice() {
 7         System.out.println("食品的价格是10元");
 8 
 9     }
10 
11 }

 1 package com.szxs.goods;
 2 /**
 3  * 电视类
 4  * @author 
 5  *
 6  */
 7 public class TVs extends Goods {
 8 
 9     public void printPrice() {
10         System.out.println("电视的价格是4998元");
11 
12     }
13 
14 }

 1 package com.szxs.goods;
 2 /**
 3  * 商场类
 4  * @author 
 5  *
 6  */
 7 public  class Mark {
 8     public Goods  buy(int type) {        
 9         Goods goods=null;
10         switch(type) {
11         case 1:
12             return goods=new Foods();            
13         case 2:
14             return goods=new TVs();
15         }
16         return goods;
17         
18     }
19 }

 1 package com.szxs.goods;
 2 
 3 public class Test {
 4 
 5     public static void main(String[] args) {
 6         Mark m=new Mark();
 7         m.buy(1).printPrice();
 8     }
 9 
10 }