Java面向对象抽象类实例练习详解编程语言

 1 abstract class Animal 
 2 { 
 3     abstract void eat(); 
 4 } 
 5  
 6 class Cat extends Animal 
 7 { 
 8     void eat() 
 9     { 
10         System.out.println("eat fish"); 
11     } 
12 } 
13  
14 class Dog extends Animal 
15 { 
16     void eat() 
17     { 
18         System.out.println("gnaw bone"); 
19     } 
20 } 
21  
22 class Pig extends Animal 
23 { 
24     void eat() 
25     { 
26         System.out.println("eat rice"); 
27     } 
28 } 
29  
30 class Duotai 
31 { 
32     public static void main(String[] args) 
33     { 
34         method(new Cat()); 
35         method(new Dog()); 
36         method(new Pig()); 
37     } 
38     public static void method(Animal a) 
39     { 
40         a.eat(); 
41     } 
42 }