初学java之接口基础

/*
长城牌电视机
联想奔月5008PC机
*/


 package st;
 //接口回调实例
 interface ShowMessage
 {
   void 显示商标 (String s);
 }
 class TV implements ShowMessage
 {
     public void 显示商标(String s)
     {
      System.out.println(s); 
     }
 }
 class PC implements ShowMessage
 {
     public void 显示商标 (String s)
     {
      System.out.println(s);
     }
 }
 public class example_1
 {
   public static void main(String args[])
   {
       ShowMessage sm;   //声明接口变量
       sm=new TV();   //接口变量中存放对象的引用
       sm.显示商标("长城牌电视机");  //接口回调
       sm=new PC();    
       sm.显示商标("联想奔月5008PC机");       
   }  
 }

/*
 * 对于接口理解的一个列子
 * 详情请关注龚细军（Gxjun）的博客
 * */ 
 package st;
 
  abstract class Motorvehicles
 {
   abstract void brake();
 }
//  接口1
 interface ControlTemperature
 {
    void ControlAirTemperature();
 }
 //接口2
 interface MonenyFare
 {
   void Charge();
 }
 class Bus extends Motorvehicles implements MonenyFare
 {
     void brake()
     {
       System.out.println("公交车来啦！,嘟嘟");
     }
    public void Charge()
    {
     System.out.println("公交车收费为5毛");
    }
 }
 class taxi extends Motorvehicles implements MonenyFare , ControlTemperature
 {
    
     void brake()
     {
       System.out.println("taxi来啦！,嘟嘟");
     }
     public void Charge()
    {
     System.out.println("taxi收费为5毛");
    }
    public void ControlAirTemperature()
    {
      System.out.println("taxi执行温度控制开关！");        
    }
 }
 class Cinema implements MonenyFare , ControlTemperature
 {
        public void Charge()
        {
         System.out.println("电影院收费为5毛");
        }
        public void ControlAirTemperature()
        {
          System.out.println("电影院执行温度控制开关！");        
        }
 }
public class example_1 {
  public  static void main(String args[])
   {
      Bus myBus = new Bus();
      taxi mytaxi = new taxi();
      Cinema mycinema = new Cinema();
      myBus.brake();
      myBus.Charge();
      mytaxi.brake();
      mytaxi.Charge();
      mytaxi.ControlAirTemperature();
      mycinema.Charge();
      mycinema.ControlAirTemperature();
   }
}

  

/*
公交车来啦！,嘟嘟
公交车收费为5毛
taxi来啦！,嘟嘟
taxi收费为5毛
taxi执行温度控制开关！
电影院收费为5毛
电影院执行温度控制开关！
*/

 接口与多态：

/*
11.23 22.78
a和b的算术平均值为：17.005000000000003
a和b的几何平均值为:15.99435525427643

*/


  package st ;
  import java.util.Scanner;
  interface c_average
  {
    public double average(double a, double b);
  }
//  求算术平均值
  class A implements c_average
  {
      public double average(double a , double b)
      { 
         return (a+b)/2; 
      }
  }
  class B implements c_average
  {
      public double average(double a,double b)
      {
          return Math.sqrt(a*b);
      }
  }
  public class example_1
  {
      public static void main(String args[])
      {
          Scanner reader=new Scanner(System.in);
          double a,b;
          a=reader.nextDouble();
          b=reader.nextDouble();
          A  mya = new A();
          System.out.println("a和b的算术平均值为："+mya.average(a, b));
          B myb=new B();
          System.out.println("a和b的几何平均值为:"+myb.average(a,b));
      }
  }