BJP wrote:
> I'm writing an application where real-time knowledge of the GPS state
> is critical to convey to the user. I request GPS updates at 1000 ms
> intervals -- when I haven't received another update 1500 ms past the
> most recent update, I want to display a yellow icon, and 5000 ms after
> the most recent update I want to display a red icon. Currently, I'm
> doing it like this:
>
> private CountDownTimer gpstimeout;
>
> public void onLocationChanged(Location location) {
> if (gpstimeout != null) gpstimeout.cancel();
> gpstimeout = new CountDownTimer(5000, 1500) {
> public void onTick(long m) { setYellow(); }
> public void onFinish() { setRed(); }
> };
> gpstimeout.start();
> }
>
> This works well (except that onTick appears to be called immediately
> on creation of the new CountDownTimer), but it seems like creating and
> destroying a new thread every second wouldn't be the best way to do
> things. Is there a better approach to this?
Here is how I would approach it, FWIW:
Step #1: Have a private long data member named lastFix in your activity.
Step #2: Update lastFix to be the current time in onLocationChanged().
Step #3: Use postDelayed() on View to set up a periodic quasi-loop
(i.e., the Runnable to postDelayed() calls postDelayed() to reschedule
the same Runnable after your desired period)
Step #4: The Runnable from Step #3 can then look at lastFix and update
your UI as needed if your fix gets stale
I would not go *too* tight on this quasi-loop. I have used a one-second
loop this way with no ill effects, but I would be nervous about it
being, say, every 100ms.
--
Mark Murphy (a Commons Guy)
http://commonsware.com | http://twitter.com/commonsguy
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