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");
    }
  }

接口回调

 /*
  * 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));
       }
   }
  

接口与多态