向上造型演示

 1 package oo.day04;
 2 //向上造型演示
 3 public class UpDemo {
 4     public static void main(String[] args) {
 5         /*
 6         Eoo o1 = new Eoo();
 7         o1.e = 1;
 8         o1.show();
 9         */
10         
11         /*
12         Foo o2 = new Foo();
13         o2.f = 1;
14         o2.say();
15         o2.e = 2;
16         o2.show();
17         */
18         
19         Eoo o3 = new Foo(); //向上造型
20         o3.e = 1;
21         o3.show();
22         //o3.f = 2; //编译错误，点出来什么，看引用的类型
23     }
24 }
25 
26 class Eoo{
27     int e;
28     void show(){
29     }
30 }
31 class Foo extends Eoo{
32     int f;
33     void say(){
34     }
35 }