【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~~