Count Down Timer

Creating a simple countdown timer

CountDownTimer is useful for repeatedly performing an action in a steady interval for a set duration. In this example, we will update a text view every second for 30 seconds telling how much time is remaining. Then when the timer finishes, we will set the TextView to say "Done."

TextView textView = (TextView)findViewById(R.id.text_view);

CountDownTimer countDownTimer = new CountDownTimer(30000, 1000) {
    public void onTick(long millisUntilFinished) {
        textView.setText(String.format(Locale.getDefault(), "%d sec.", millisUntilFinished / 1000L));
    }

    public void onFinish() {
        textView.setText("Done.");
    }
}.start();

A More Complex Example

In this example, we will pause/resume the CountDownTimer based off of the Activity lifecycle.

private static final long TIMER_DURATION = 60000L;
private static final long TIMER_INTERVAL = 1000L;

private CountDownTimer mCountDownTimer;
private TextView textView;

private long mTimeRemaining;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    textView = (TextView)findViewById(R.id.text_view); // Define in xml layout.

    mCountDownTimer = new CountDownTimer(TIMER_DURATION, TIMER_INTERVAL) {
        
        @Override
        public void onTick(long millisUntilFinished) {
            textView.setText(String.format(Locale.getDefault(), "%d sec.", millisUntilFinished / 1000L));
            mTimeRemaining = millisUntilFinished; // Saving timeRemaining in Activity for pause/resume of CountDownTimer.
        }

        @Override
        public void onFinish() {
            textView.setText("Done.");
        }
    }.start();
}


@Override
protected void onResume() {
    super.onResume();
    
    if (mCountDownTimer == null) { // Timer was paused, re-create with saved time.
        mCountDownTimer = new CountDownTimer(timeRemaining, INTERVAL) {
            @Override
            public void onTick(long millisUntilFinished) {
                textView.setText(String.format(Locale.getDefault(), "%d sec.", millisUntilFinished / 1000L));
                timeRemaining = millisUntilFinished;
            }

            @Override
            public void onFinish() {
                textView.setText("Done.");
            }
        }.start();
    }
}

@Override
protected void onPause() {
    super.onPause();
    mCountDownTimer.cancel();
    mCountDownTimer = null;
}

Parameters

Parameter	Details
long millisInFuture	The total duration the timer will run for, a.k.a how far in the future you want the timer to end. In milliseconds.
long countDownInterval	The interval at which you would like to receive timer updates. In milliseconds.
long millisUntilFinished	A parameter provided in onTick() that tells how long the CountDownTimer has remaining. In milliseconds

Remarks

CountDownTimer is a pretty lean class - it does one thing very well. Since you can only start/cancel a CountDownTimer, you have to implement pause/resume functionality as shown in the second example. For more complex functionality, or to specify a timer that should run indefinitely, use the Timer (opens new window) object.