如何实现倒计时运行超出限制？

Question

我正在开发一个应用程序，在该应用程序中我使用CountDownTimer 用于计时器目的，它从给定的开始时间运行到 0，然后在onFinish() 中接收回调，但我希望它以负值运行。比如说，如果计时器设置为 1 分钟并且它结束了，那么它应该继续 -ve 值而不是弯腰倒计时。

如何做到这一点，或者有其他方法吗？

Answer 1

对不起，回答晚了，但我希望这对那些也和这个问题一样的人有帮助。

Fist android 提供CountDownTimer 类来执行倒计时操作。在这个类中，计时器在时间为 0 小时、0 分钟、0 秒和 onFinish() 方法调用时停止。
所以如果我们想输入负值，我们需要一些行来注释掉意味着我们必须为倒数计时器制作我们的自定义类。所以这里是自定义类，它也可以是负值。只需在您的项目中将其过去并导入此类而不是原始的 CountDownTimer 类。

import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;


public abstract class CustomCountDownTimer {
    /**
     * Millis since epoch when alarm should stop.
     */
    private final long mMillisInFuture;

    /**
     * The interval in millis that the user receives callbacks
     */
    private final long mCountdownInterval;

    private long mStopTimeInFuture;

    /**
     * boolean representing if the timer was cancelled
     */
    private boolean mCancelled = false;

    /**
     * @param millisInFuture    The number of millis in the future from the call
     *                          to {@link #start()} until the countdown is done and {@link #onFinish()}
     *                          is called.
     * @param countDownInterval The interval along the way to receive
     *                          {@link #onTick(long)} callbacks.
     */
    public CustomCountDownTimer(long millisInFuture, long countDownInterval) {
        mMillisInFuture = millisInFuture;
        mCountdownInterval = countDownInterval;
    }

    /**
     * Cancel the countdown.
     */
    public synchronized final void cancel() {
        mCancelled = true;
        mHandler.removeMessages(MSG);
    }

    /**
     * Start the countdown.
     */
    public synchronized final CustomCountDownTimer start() {
        mCancelled = false;

        //if (mMillisInFuture <= 0) {
        //onFinish();
        //return this;
        //}

        mStopTimeInFuture = SystemClock.elapsedRealtime() + mMillisInFuture;
        mHandler.sendMessage(mHandler.obtainMessage(MSG));
        return this;
    }


    /**
     * Callback fired on regular interval.
     *
     * @param millisUntilFinished The amount of time until finished.
     */
    public abstract void onTick(long millisUntilFinished);

    /**
     * Callback fired when the time is up.
     */
    public abstract void onFinish();


    private static final int MSG = 1;


    // handles counting down
    private Handler mHandler = new Handler() {

        @Override
        public void handleMessage(Message msg) {

            synchronized (CustomCountDownTimer.this) {
                if (mCancelled) {
                    return;
                }

                final long millisLeft = mStopTimeInFuture - SystemClock.elapsedRealtime();

                //if (millisLeft <= 0) {
                //  onFinish();
                //} else
                //        if (millisLeft < mCountdownInterval) {
                // no tick, just delay until done
                //      sendMessageDelayed(obtainMessage(MSG), millisLeft);
                //      } else {
                long lastTickStart = SystemClock.elapsedRealtime();
                onTick(millisLeft);

                // take into account user's onTick taking time to execute
                long delay = lastTickStart + mCountdownInterval - SystemClock.elapsedRealtime();

                // special case: user's onTick took more than interval to
                // complete, skip to next interval
                while (delay < 0) delay += mCountdownInterval;

                sendMessageDelayed(obtainMessage(MSG), delay);
                //   }
            }
        }
    };
}

重要：这里我们从条件中删除onFinish() 方法，所以它不会完成你必须根据你的要求调用onFinsh() 方法