I have the following code
class OverlayTask extends AsyncTask<Void, Void, Void> {
@Override
public void onPreExecute() {
if (sites != null) {
myMapView.getOverlays().remove(sites);
myMapView.invalidate();
sites = null;
}
}
@Override
public Void doInBackground(Void... unused) {
grabShipsWithLocation();
return (null);
}
@Override
public void onPostExecute(Void unused) {
myMapView.getOverlays().add(sites);
myMapView.invalidate();
isLoading = false;
}
}
That seems to work fine on a few test devices but I am seeing a lot of errors appearing on the dev console. I can't seem to work out why and where to put this Looper.prepare(). Is it needed?
java.lang.ExceptionInInitializerError
at com.test.appname.FinderMain$1.gotLocation(FinderMain.java:286)
at com.test.appname.MyLocation$GetLastLocation.run(MyLocation.java:89)
at java.util.Timer$TimerImpl.run(Timer.java:289)
Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
at android.os.Handler.<init>(Handler.java:121)
at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:421)
at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:421)
at android.os.AsyncTask.<clinit>(AsyncTask.java:152)
As requested MyLocation.java
class GetLastLocation extends TimerTask {
@Override
public void run() {
lm.removeUpdates(locationListenerGps);
lm.removeUpdates(locationListenerNetwork);
Location net_loc=null, gps_loc=null;
if(gps_enabled)
gps_loc=lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if(network_enabled)
net_loc=lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
//if there are both values use the latest one
if(gps_loc!=null && net_loc!=null){
if(gps_loc.getTime()>net_loc.getTime())
locationResult.gotLocation(gps_loc);
else
locationResult.gotLocation(net_loc);
return;
}
if(gps_loc!=null){
locationResult.gotLocation(gps_loc); //Line 89
return;
}
if(net_loc!=null){
locationResult.gotLocation(net_loc);
return;
}
locationResult.gotLocation(null);
}
}
Long story:
AsyncTask
internally uses a Handler
. A handler basically allows you to post Runnables
from another thread on the thread the handler was assigned to, which in the case of AsyncTask
is always the thread from which it is called. This only works for threads that have a Looper
prepared, though.
For more information see http://developer.android.com/reference/android/os/Handler.html
Short story:
Simply wrap every call to FinderMain$1.gotLocation
or the creation of AsyncTask
within it in a Runnable
, and post it to a Handler
bound to the UI thread, like this:
class GetLastLocation extends TimerTask {
private Handler mHandler = new Handler(Looper.getMainLooper());
@Override
public void run() {
// ...
mHandler.post(new Runnable() {
public void run() {
locationResult.gotLocation(null);
}
});
// ...
}
}