Why is my milliseconds count down not consistent?

Question

For some reason my timer does not count down consistantly, it sometimes goes back to the previous second or so.

For example: if I begin the timer at 49 seconds this is whats printed out:

(in milliseconds)

48774
47374
48909 //inconsistent

47063
46212
44987
48426 //inconsistent

46294 //inconsistent

44738
43636
42410
...and so on

All I do it pass in two integers (minutes and seconds) and combine them together to get the total number of milliseconds.

Here is my code:

new CountDownTimer(((min * 60 + sec) * 1000), 1000) {//total time, interval

                public void onTick(long millisUntilFinished) {
                    System.out.println(millisUntilFinished);
                //...
                }
}

How can I get the milliseconds to display consistently?

EDIT:

I have also tried adding this to onTick but it still does not work

if((int)prevMill > (int)millisUntilFinished){
        prevMill = millisUntilFinished;
        System.out.println(prevMill);
 }

Because, in general, the system clock is only accurate +/- 15ms. You could round to the nearest 15, and it should be consistent. — Elliott Frisch, Feb 28 '16 at 05:33
But there must be some way to make it display correctly, I mean our phones already have timers that countdown without any inconsistencies. — bob dylan, Feb 28 '16 at 05:35

score 3 · Accepted Answer · edited May 23 '17 at 12:31

3

I found that onTick() is calculated from the time the previous onTick() ran, which creates a tiny error on every tick.

See this post: android CountDownTimer - additional milliseconds delay between ticks

edited May 23 '17 at 12:31

Community

1
1

answered Feb 28 '16 at 05:34

fman

230
2
10

This would explain the interval not being exact, but not the increasing value of millisUntilFinished. My best guess is that Dylan accidentally starts multiple countdowns. – Snild Dolkow Feb 28 '16 at 06:11

score 0 · Answer 2 · answered Feb 28 '16 at 05:36

Even though you specify values to the millisecond in APIs like that, by default the system timer is only going to have about +/-15ms resolution (varies by OS, etc).

This can be changed, see here: https://randomascii.wordpress.com/2013/07/08/windows-timer-resolution-megawatts-wasted/

Why is my milliseconds count down not consistent?

2 Answers2