Why does the following Count down timer in android always shows 00:01 at the end?

Question

String hms = String.format("%02d:%02d",
                    TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(millisUntilFinished)),
                    TimeUnit.MILLISECONDS.toSeconds(millisUntilFinished) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished)));

I seriously don't get

1) How minutes - hours work TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(millisUntilFinished))

2) Why does it always ends with 00:01?

3) How does onTick() method of CountDowntimer gets called?

Answer 1

1) How minutes - hours work TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(millisUntilFinished))

• Don't know why you did this. You can just write

  String hms = String.format("%02d:%02d", TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished), TimeUnit.MILLISECONDS.toSeconds(millisUntilFinished) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished)));

2) Why does it always ends with 00:01?

Yes you are right! In the countdown timer last call will not trigger the onTick() method it will call the below method.

 public void onFinish() {
    mTextField.setText("00:00");
}

So you can set "00:00" at the onFinish() method shown in the above snippet.

3) How does onTick() method of CountDowntimer gets called?

-onTick() Callback fired on regular interval provided to the CountDowntimer constructor.