【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：

1 // 电池类
2 class Battery
3 {
4     // 充电
5     public void chargeBattery(double p)
6     {
7         power += p;
8         System.out.println("Battery: power is " + power );
9     }
10     // 放电
11     public boolean useBattery(double p)
12     {
13         if (power >p )
14         {
15             power -= p;
16             System.out.println("Battery: power is " + power );
17             return true;
18         }
19         else
20         {
21             power = 0.0;
22             System.out.println("Battery: power only is " + power +", not enough");
23             return false;
24         }
25     }
26     // 电量
27     private double power = 0.0;
28 }
29
30
31 // 手电筒类
32 class Torch
33 {
34     // 打开手电筒
35     public void turnon(int hours)
36     {
37         System.out.println("Torch:turnon " + hours + " hours.");
38
39         if ( theBattery.useBattery( hours*0.1) == false )
40         {
41             System.out.println("Torch:can not use, please charge! ");
42         }
43     }
44
45     //手电充电
46     public void charge(int hours)
47     {
48         System.out.println("Torch:charge " + hours + " hours.");
49         theBattery.chargeBattery( hours*0.2 );
50     }
51
52     //电池类
53     private Battery theBattery = new Battery();
54 }
55
56
57 public class test
58 {
59     public static void main(String[] args)
60     {
61         Torch aTorch = new Torch();
62         aTorch.charge(2);
63         aTorch.turnon(3);
64         aTorch.turnon(3);
65     }
66
67 }

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~~