java

接口的实现、继承等

 1 package test.interfacedemo;
 2 import test.interfacedemo.Inter;
 3 
 4 public class InterfaceDemo {
 5     public static void main(String[] args){
 6         Inter o1 = new Foo();  //Foo实现接口Inter,类同于 向上造型
 7                                //通过变量o1可以调用接口Inter中定义的方法和常量
 8         System.out.println(Inter.PI);
 9         
10         Inter3 t = new Boo();  //Boo实现接口Inter3
11         t.a();
12         t.c();
13     }
14 }

 1 package test.interfacedemo;
 2 
 3 public interface Inter{  //接口定义
 4     public static final double PI = 3.14;
 5     int NUM = 5;
 6     public abstract void show();
 7     void say(); //省略public abstract
 8 }
 9 
10 class  Foo implements Inter{
11     public void show(){}
12     public void say(){}
13 }
14 
15 interface Inter1{
16     public abstract void a();
17 }
18 interface Inter2{
19     public abstract void b();
20 }
21 interface Inter3 extends Inter1{
22     public abstract void c();
23 }
24 
25 abstract class Aoo{
26     void d(){}
27     abstract void e();
28 }
29 class Boo implements Inter3{
30     void m(){}
31     public void a(){
32         System.out.println("a");
33     }
34     public void c(){
35         System.out.println("c");
36     }
37 }
38 class Coo implements Inter1,Inter2{
39     public void a(){}
40     public void b(){}    
41 }
42 class Doo extends Aoo implements Inter1,Inter2{
43     void e(){}
44     public void a(){}
45     public void b(){}
46 }