为什么我的继承应用程序不起作用？

Question

我正在做一个过去的学校作业，它是关于一个带有子类时钟的微波应用程序。不知何故，我对自己的代码感到困惑，完全迷失了方向。有人可以帮我解决这些吗？谢谢！

首先是时钟类。

class Clock extends Microwave {

private int hour;
private int minute;
private int second;

Clock()
{
    hour = 0;
    minute = 0;
    second = 0;     
}

Clock(int h, int m, int s)
{
    hour = h;
    minute = m;
    second = s;
}

public int getHour()
{
    return hour;
}

public int getMin()
{
    return minute;
}

public int getSec()
{
    return second;
}

public String toString()
{
    return (String.valueOf(second));
}

protected void tick()
{
    second++;

    if(hour == 23 && minute == 59 && second == 59)
    {
        hour = 0;
        minute = 0;
        second = 0;
    } else if(minute == 59 && second == 59)
    {
        hour++;
        minute = 0;
        second = 0;
    } else if(second == 59)
    {
        minute++;
        second = 0;
    }
}
}

接下来是父类 Microwave。

class Microwave {

private int maxPower;
private int currentPower;
private Clock theClock;

Microwave()
{
    maxPower = 500;
    currentPower = 500;
    theClock = new Clock();
}

Microwave(int maxp, Clock theClock)
{
    maxPower = maxp;
    currentPower = maxPower;
    theClock = new Clock();
}

public int getCurrentPower()
{
    return currentPower;
}

public int getMaxPower()
{
    return maxPower;
}

public String getTime()
{
    return "The time is " + theClock.getHour() + ":" + theClock.getMin() + ":" + theClock.getSec();
}

protected void cook(int p, int t)
{
    if(p < maxPower)
    {
        currentPower = p;
    } else
    {
        System.exit(0);
    }

    for(int i = 0; i < t; i++)
    {
        theClock.tick();
    }
}
}

最后是main方法类。

class TestMicrowave
{
 public static void main(String []args)
 { 
    Clock  c = new Clock(14, 30,30);
    Microwave  m = new Microwave(750, c);
    System.out.println("The microwave is currently at " + 
                     m.getCurrentPower() + " watts and "+ m.getTime());


     m.cook(600,45);    // should advance time to  14:31:15

     System.out.println(m.getTime());

     m.cook(800,45);    // shoudln't cook as power > maxPower
     System.out.println(m.getTime());

 }
 }

我认为，我在 Microwave 类中的 getTime() 方法有问题，但我不知道它有什么问题。 提前致谢！

Answer 1

时钟不是子类。微波炉由时钟组成。从 Clock 类中删除“extends Microwave”。

在这个设计中不应该有任何继承。

Answer 2

继承建议是垃圾，您应该改为编写时钟（微波炉可能包含时钟，因为您的 Microwave 类已经编写），所以从您的 Clock 类中删除 extends Microwave。

除了这个问题，另一个问题是您的 CTOR：

Microwave()
{
    maxPower = 500;
    currentPower = 500;
    theClock = new Clock();
}

Microwave(int maxp, Clock theClock)
{
    maxPower = maxp;
    currentPower = maxPower;
    //theClock = new Clock(); // you're passing a reference to this already, so by using this call you replace it with a new instance via the default ctor of Clock().
    this.theClock = theClock;
}

Answer 3

接受Clock 参数的构造函数将丢弃它，因此您始终从零时钟开始。

Microwave(int maxp, Clock clock)
{
    maxPower = maxp;
    currentPower = maxPower;
    this.theClock = clock;
}