c# - 有问题的 if 语句

Question

我之前尝试过问这个问题两到三遍，但无法正确地解决这个问题，所以我想再试一次。我正在制作一个训练秒表应用程序。该应用程序的功能是计算10秒，让学员有10秒的准备时间。一旦该时间过去，它计为 20 秒，受训者在 20 秒内进行了艰苦的锻炼。之后，有 10 秒的休息时间。然后它循环回到 20 秒的锻炼并继续这个循环 8 轮。

我的问题是它将开始 10 秒准备，但随后又循环回到 10 秒计时器。出于某种原因，我的 if else 语句不断循环回到准备时间。
我在 if 语句中使用秒表和时间跨度。

private void timer_Tick(object sender, EventArgs e)
    {
        //throw new NotImplementedException();
        //timer timespan is more than zero, start stopwatch(get the prepare counter going)
        if (timerWatch.Elapsed < new TimeSpan(0, 0, 11))// if its 5sec
        {
            milllisecond = timerWatch.ElapsedMilliseconds;
            second = milllisecond / 1000;
            milllisecond = milllisecond % 1000;
            minute = second / 60;
            second = second % 60;
            hour = minute / 60;
            minute = minute % 60;
            txtblTime.Text = minute.ToString("00") + ":" + second.ToString("00");
        }
        else if (timerWatch.Elapsed >= new TimeSpan(0, 0, 10) && timerWatch.Elapsed < new TimeSpan(0, 0, 21))//more than 4sec
        {
            timerWatch.Restart();

            milllisecond = timerWatch.ElapsedMilliseconds;
            second = milllisecond / 1000;
            milllisecond = milllisecond % 1000;
            minute = second / 60;
            second = second % 60;
            hour = minute / 60;
            minute = minute % 60;
            txtblTime.Text = minute.ToString("00") + ":" + second.ToString("00");

            txtblPrepare.Visibility = System.Windows.Visibility.Collapsed;
            txtblGo.Visibility = System.Windows.Visibility.Visible;
        }
        else if (timerWatch.Elapsed < new TimeSpan(0, 0, 21))
        {
            timerWatch.Restart();

            milllisecond = timerWatch.ElapsedMilliseconds;
            second = milllisecond / 1000;
            milllisecond = milllisecond % 1000;
            minute = second / 60;
            second = second % 60;
            hour = minute / 60;
            minute = minute % 60;

            txtblTime.Text = minute.ToString("00") + ":" + second.ToString("00");
            txtblGo.Visibility = System.Windows.Visibility.Collapsed;
        }
        else
            txtblTime.Text = "Times Up!";                    
    }

Answer 1

您要实现的是所谓的 finite-state machine .从定时器推断这台机器的状态使得代码难以理解和阅读。我会以更直接的方式存储状态。正如 Plutonix 所说，使用枚举

public enum TrainingState
{
    Stopped, // The state machine is not working yet or has finished its work.
    Preparing,
    Working,
    Resting
}

此外，您将需要一个计数器来计算循环次数

private TrainingState _state = TrainingState.Stopped;
private int _roundNo;

现在您可以像这样制定状态转换

private void ChangeState()
{
    switch (_state) {
        case  TrainingState.Stopped:
            //TODO: Initialize and start the timer, display state
            _state = TrainingState.Preparing;
            break;
        case  TrainingState.Preparing:
            //TODO: Adjust timer intervall for working phase, display state
            _roundNo = 1; // We are going into the first round
           _state = TrainingState.Working;
            break;
        case  TrainingState.Working:
             //TODO: Adjust timer intervall for resting phase, display state
            _state = TrainingState.Resting;
            break;
        case  TrainingState.Resting:
            if (_roundNo == 8) {
                _state = TrainingState.Stopped;
                //TODO: stop timer, display state
            } else {
                //TODO: Adjust timer intervall for working phase, display state
                _roundNo++; // We are going into the next round
               _state = TrainingState.Working;
            }
            break;
    }
}

您必须在启动时和内部调用此方法 timer_Tick .

private void timer_Tick(object sender, EventArgs e)
{
    ChangeState();
}

private void btnStart_Click(object sender, EventArgs e)
{
    ChangeState();
}