对象交互

模拟时钟运行

一个clock类里面有两个display类，分别是时针分针，通过clock实现两个时针(对象)，分针(对象）的交互. 

两个对象互相不相关,通过比它们更高级的clock来实现交互

一个clock工程里面一个clock包，里边两个类，一个display类，一个clock类. 

1.  package clock;
   public class display {
       private int value = 0;
       private int limit = 0;
       
       public display(int limit) {
           this.limit=limit;
       }
       
       public void increase()
       {
           value++;
           if(value == limit)
           {
               value = 0;
           }
       }
       
       public int getValue() {
           return value;
       }
       public static void main(String[] args) {
           display d = new display(24);
           for(;;) {
               d.increase();
               System.out.println(d.getValue());
           }
    
       }
    
   } 

   package Clocks;
   
   public class Clock 
   {
       private Display hour = new Display(24);
       private Display minute = new Display(60);
       private Display second = new Display(60);
       public void start()
       {
           while(true)
               
           {
               second.increase();
               
               if (second.getValue()==0)
               {
                   minute.increase();
                   
                   if(minute.getValue()==0)
                   {
                       hour.increase();
                   }
                   
               }
               System.out.printf("%02d:%02d:%02d
   ",hour.getValue(),minute.getValue(),second.getValue());
               
               
           }
       
       }
       
   
       public static void main(String[] args) {
           
           Clock clock = new Clock();
           clock.start();
   
       }
   
   }

    参考：https://blog.csdn.net/weixin_41183791/article/details/82818115