【Java 基础篇】【第七课】组合

我所理解的组合就是在一个类当中又包含了另一个类的对象。

这样的方式就是组合吧：

电池是一个类，有电量

手电筒需要电池

看代码吧：

 // 电池类
 class Battery
 {
     // 充电
     public void chargeBattery(double p)
     {
         power += p;
         System.out.println("Battery: power is " + power );
     }
     // 放电
     public boolean useBattery(double p)
     {
         if (power >p )
         {
             power -= p;
             System.out.println("Battery: power is " + power );
             return true;
         }
         else
         {
             power = 0.0;
             System.out.println("Battery: power only is " + power +", not enough");
             return false;
         }
     }
     // 电量
     private double power = 0.0;
 }

 // 手电筒类
 class Torch
 {
     // 打开手电筒
     public void turnon(int hours)
     {
         System.out.println("Torch:turnon " + hours + " hours.");

         if ( theBattery.useBattery( hours*0.1) == false )
         {
             System.out.println("Torch:can not use, please charge! ");
         }
     }

     //手电充电
     public void charge(int hours)
     {
         System.out.println("Torch:charge " + hours + " hours.");
         theBattery.chargeBattery( hours*0.2 );
     }

     //电池类
     private Battery theBattery = new Battery();
 }

 public class test
 {
     public static void main(String[] args)
     {
         Torch aTorch = new Torch();
         aTorch.charge(2);
         aTorch.turnon(3);
         aTorch.turnon(3);
     }

 }

运行结果为：
Torch:charge 2 hours.
Battery: power is 0.4
Torch:turnon 3 hours.
Battery: power is 0.09999999999999998
Torch:turnon 3 hours.
Battery: power only is 0.0, not enough
Torch:can not use, please charge!

主要就是一个面向对象的一个思想，很好理解~~