1 /*
 2 长城牌电视机
 3 联想奔月5008PC机
 4 */
 5 
 6 
 7  package st;
 8  //接口回调实例
 9  interface ShowMessage
10  {
11    void 显示商标 (String s);
12  }
13  class TV implements ShowMessage
14  {
15      public void 显示商标(String s)
16      {
17       System.out.println(s); 
18      }
19  }
20  class PC implements ShowMessage
21  {
22      public void 显示商标 (String s)
23      {
24       System.out.println(s);
25      }
26  }
27  public class example_1
28  {
29    public static void main(String args[])
30    {
31        ShowMessage sm;   //声明接口变量
32        sm=new TV();   //接口变量中存放对象的引用
33        sm.显示商标("长城牌电视机");  //接口回调
34        sm=new PC();    
35        sm.显示商标("联想奔月5008PC机");       
36    }  
37  }

 1 /*
 2  * 对于接口理解的一个列子
 3  * 详情请关注龚细军（Gxjun）的博客
 4  * */ 
 5  package st;
 6  
 7   abstract class Motorvehicles
 8  {
 9    abstract void brake();
10  }
11 //  接口1
12  interface ControlTemperature
13  {
14     void ControlAirTemperature();
15  }
16  //接口2
17  interface MonenyFare
18  {
19    void Charge();
20  }
21  class Bus extends Motorvehicles implements MonenyFare
22  {
23      void brake()
24      {
25        System.out.println("公交车来啦！,嘟嘟");
26      }
27     public void Charge()
28     {
29      System.out.println("公交车收费为5毛");
30     }
31  }
32  class taxi extends Motorvehicles implements MonenyFare , ControlTemperature
33  {
34     
35      void brake()
36      {
37        System.out.println("taxi来啦！,嘟嘟");
38      }
39      public void Charge()
40     {
41      System.out.println("taxi收费为5毛");
42     }
43     public void ControlAirTemperature()
44     {
45       System.out.println("taxi执行温度控制开关！");        
46     }
47  }
48  class Cinema implements MonenyFare , ControlTemperature
49  {
50         public void Charge()
51         {
52          System.out.println("电影院收费为5毛");
53         }
54         public void ControlAirTemperature()
55         {
56           System.out.println("电影院执行温度控制开关！");        
57         }
58  }
59 public class example_1 {
60   public  static void main(String args[])
61    {
62       Bus myBus = new Bus();
63       taxi mytaxi = new taxi();
64       Cinema mycinema = new Cinema();
65       myBus.brake();
66       myBus.Charge();
67       mytaxi.brake();
68       mytaxi.Charge();
69       mytaxi.ControlAirTemperature();
70       mycinema.Charge();
71       mycinema.ControlAirTemperature();
72    }
73 }

 1 /*
 2 11.23 22.78
 3 a和b的算术平均值为：17.005000000000003
 4 a和b的几何平均值为:15.99435525427643
 5 
 6 */
 7 
 8 
 9   package st ;
10   import java.util.Scanner;
11   interface c_average
12   {
13     public double average(double a, double b);
14   }
15 //  求算术平均值
16   class A implements c_average
17   {
18       public double average(double a , double b)
19       { 
20          return (a+b)/2; 
21       }
22   }
23   class B implements c_average
24   {
25       public double average(double a,double b)
26       {
27           return Math.sqrt(a*b);
28       }
29   }
30   public class example_1
31   {
32       public static void main(String args[])
33       {
34           Scanner reader=new Scanner(System.in);
35           double a,b;
36           a=reader.nextDouble();
37           b=reader.nextDouble();
38           A  mya = new A();
39           System.out.println("a和b的算术平均值为："+mya.average(a, b));
40           B myb=new B();
41           System.out.println("a和b的几何平均值为:"+myb.average(a,b));
42       }
43   }
44