Um. Don't do that. AsyncTask and Looper are two fundamentally different
threading models, which are not compatible. If you want a thread running a
looper, use HandlerThread.
On Tue, Oct 27, 2009 at 10:53 AM, szabolcs <szabolcs.vr...@gmail.com> wrote:
>
> Hello,
>
> I ran into some trouble trying to use a Looper inside an AsyncTask
> (its doInBackground method). Everything works fine until new Tasks are
> being created by AsyncTask.sThreadFactory, but once I reach the
> AsyncTask.CORE_POOL_SIZE limit and AsyncTask begins to recycle the
> threads, sending messages to my looper (created inside doInBackground)
> results in a MessageQueue RuntimeException: "sending message to a
> Handler on a dead thread".
>
> The code I tried was:
>
> DaTask extends AsyncTask {
>
> // NOTE: there is only one DaTask being executed at any time,
> // but DaTask is created/executed sequentially multiple times.
> public static Looper mLooper;
>
> @Override
> protected void onPreExecute() {
> mHandler = new Handler() {
> @Override
> public void handleMessage(Message msg) {
> ...
> case MSG_EXIT:
> DaTask.mLooper.quit();
> break;
> };
> }
>
> @Override
> protected Void doInBackground(Void... params) {
> if (Looper.myLooper() == null) {
> Looper.prepare();
> }
>
> mLooper = Looper.myLooper();
>
> lm.requestLocationUpdates(
> LocationManager.GPS_PROVIDER, 0, 0,
> DaTask.this, mLooper
> );
>
> Looper.loop(); // process location updates
> }
>
> The idea was to create a handler (the same way as the InternalHandler
> () is created in the constructor of the AsyncTask) that is able to
> stop a background process that performs work based on location
> updates.
>
> As far as I can tell, the Looper that was registered as a ThreadLocal
> during the first/successful run of DaTask is obtained properly even
> during the second/unsuccessful run. However, it seems like it does not
> process the messages. Why? Can a Looper not be 'restarted'? Looking at
> the source of Looper.loop(), it seemes to me that it should be able
> to.
>
> I am surely missing something here..
>
> Thank you kindly for any suggestions,
>
> -szabolcs
>
> >
>
--
Dianne Hackborn
Android framework engineer
hack...@android.com
Note: please don't send private questions to me, as I don't have time to
provide private support, and so won't reply to such e-mails. All such
questions should be posted on public forums, where I and others can see and
answer them.
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