Question

我正在处理一个应用程序，其中我使用CountDownTimer作为计时器目的，从开始时间到最多0运行，然后在onFinish()接收回调，但我希望它运行负值。比方说，如果计时器设置为1分钟而且结束时它应该继续使用-ve值而不是弯曲倒计时器。

如何做到这一点，还是有其他方法可以做到这一点？

Answer 1

很抱歉迟到的答案，但我希望这对那些也想做同样问题的人有所帮助。

拳头android提供 CountDownTimer 类来执行倒计时器操作。在此课程计时器停止时，时间为0小时，0分钟，0秒和onFinish()方法调用因此，如果我们想要减去值，我们需要一些注释掉的方法，换句话说，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，也可以在负值。刚刚在项目中使用它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：此处我们从条件中移除onFinish()方法，因此无法完成您必须根据您的要求调用onFinsh()方法

如何实现coundowntimer超越极限？

1 个答案: