Java abstract关键字

 1 public abstract class Telphone{
 2     public abstract void call();
 3     public abstract void message();
 4 }
 5 public class CellPhone extends Telphone{
 6     @Override
 7     public void call(){
 8     
 9     }
10     @Override
11     public void message(){
12     
13     }
14 }
15 public class SmartPhone extends Telphone{
16     @Override
17     public void call(){
18     
19     }
20     @Override
21     public void message(){
22     
23     }
24 }
25 public class Test{
26     public static void main(String[] args){
27         Telphone tp1 = new CellPhone();
28         tp1.call();
29         tp1.message();
30         Telphone tp2 = new SmartPhone();
31         tp2.call();
32         tp2.message();
33     }
34 }