Pause CountDownTimer in Android when activity is not in front

Question

I have an activity that uses a CountDownTimer that counts down from 10. How do I pause that timer when the activity is no longer in focus, like if the user get a call or som

Answer 1

This must be exactly what you're looking for. Source is this Gist.

package alt.android.os;

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

public abstract class CountDownTimer {

/**
 * 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;

private long mPauseTime;

private boolean mCancelled = false;

private boolean mPaused = 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 CountDownTimer(long millisInFuture, long countDownInterval) {
    mMillisInFuture = millisInFuture;
    mCountdownInterval = countDownInterval;
}

/**
 * Cancel the countdown.
 *
 * Do not call it from inside CountDownTimer threads
 */
public final void cancel() {
    mHandler.removeMessages(MSG);
    mCancelled = true;
}

/**
 * Start the countdown.
 */
public synchronized final CountDownTimer start() {
    if (mMillisInFuture <= 0) {
        onFinish();
        return this;
    }
    mStopTimeInFuture = SystemClock.elapsedRealtime() + mMillisInFuture;
    mHandler.sendMessage(mHandler.obtainMessage(MSG));
    mCancelled = false;
    mPaused = false;
    return this;
}

/**
 * Pause the countdown.
 */
public long pause() {
    mPauseTime = mStopTimeInFuture - SystemClock.elapsedRealtime();
    mPaused = true;
    return mPauseTime;
}

/**
 * Resume the countdown.
 */
public long resume() {
    mStopTimeInFuture = mPauseTime + SystemClock.elapsedRealtime();
    mPaused = false;
    mHandler.sendMessage(mHandler.obtainMessage(MSG));
    return mPauseTime;
}

/**
 * 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 (CountDownTimer.this) {
            if (!mPaused) {
                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;

                    if (!mCancelled) {
                        sendMessageDelayed(obtainMessage(MSG), delay);
                    }
                }
            }
        }
    }
};
}