How come millisUntilFinished cannot detect exact CountDownTimer intervals?

Hey all, so there is a rather small but annoying problem with the CountDownTimer.. Currently I have an interval set to 1000. And I am trying to detect the amount of milliseconds left in my

onTick()

method. So that I can use Text To Speech when there are 20 seconds left, 10 seconds left, etc. Well if I use:

//Speak when 20 seconds left
if (millisUntilFinished == 20000) {
    tts.speak("You have 20 seconds left.", TextToSpeech.QUEUE_FLUSH, null);
}

The timer is not able to detect the 20000 milliseconds exactly.

So I have to resort to using:

//Speak when 20 seconds left
if (millisUntilFinished < 20999) {
    if (millisUntilFinished > 19999) {
       tts.speak("You have 20 seconds left.", TextToSpeech.QUEUE_FLUSH, null);
     } 
}

The problem with that is that sometimes the text to speech will come on t开发者_JAVA百科wice during that interval. Is there any way to detect the milliseconds exactly so I dont have to use greater than or less than?

Is there any way to detect the milliseconds exactly so I dont have to use greater than or less than?

Of course not. Android is not a RTOS. Timing will be approximate, simply due to the main application thread being possibly occupied with other duties at any given moment.

If you want more flexibility you can also try something like

int secondsLeft = 0; 

new CountDownTimer(30000, 100) {
    public void onTick(long ms) {
        if (Math.round((float)ms / 1000.0f) != secondsLeft)
        {  
            secondsLeft = Math.floor((float)ms / 1000.0f);
            if (secondsLeft == 20) {
                tts.speak("You have 20 seconds left.", TextToSpeech.QUEUE_FLUSH, null);
            }
        }
    }

    public void onFinish() {
    }
}.start();

from https://stackoverflow.com/a/6811744/1189831

You could use a trick. If you use a Chronometer widget instead of a TexView, you could make something like this:

int time = 30;

Chronometer chrono = (Chronometer) findViewById(R.id.your_chronometer_id);

chrono.setOnChronometerTickListener(new Chronometer.OnChronometerTickListener() {

    @Override
    public void onChronometerTick(Chronometer chronometer) {

        chronometer.setText(String.valueOf(_time));

        if(_time == 20) tts.speak("You have 20 seconds left.", TextToSpeech.QUEUE_FLUSH, null);

        if(_time == 0){

            //Time finished, make your stuff

            chronometer.stop();     

        }else{

            _time--;

        }

    }

});