How keep a CountDownTimer running when I press the back button
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I have a CountDownTimer which updates a TextView, but when I press the back button it stops.

    CountDownTimer timer = new CountDownTimer(600000, 100) {

        public void onTick(long millisUntilFinished) {
            calendar.setTimeInMillis(millisUntilFinished);

            cron.setText(sf.format(calendar.getTime()));
        }

        public void onFinish() {
        }
    };

How can I keep it running when I press the back button and the activity gets destroyed?

PS: I also start a GPS service when the timer starts, Is there a way to put the CountDownTimer in the service?