LocationManager calling onLocationChanged too often?
I've set up the LocationManager to get the current location every 2 minutes:
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 120000, 0, this);
This works fine and onLocationChanged is called every 2 minutes as expected. However, it seems that it is being called multiple times over a 10-40 (a random amount) second span every 2 minutes. I log every location received in the onLocationChanged so here are some samples to get an idea of what is going on:
At 17:30
GPS 32.0 50.66318929195404 10.735434293746948 0.0 2010.08.07 17:30:10
GPS 32.0 50.66315710544586 10.735423564910889 0.0 2010.08.07 17:30:14
GPS 32.0 50.66314101219177 10.735418200492859 0.0 2010.08.07 17:30:17
GPS 32.0 50.66314101219177 10.735418200492859 0.0 2010.08.07 17:30:20
GPS 24.0 50.66313564777374 10.735418200492859 0.5 2010.08.07 17:30:24
GPS 32.0 50.663098096847534 10.735573768615723 0.0 2010.08.07 17:30:28
GPS 32.0 50.663065910339355 10.735611319541931 0.0 2010.08.07 17:30:31
Then I get no more updates for 2 minutes.
At 17:32
GPS 32.0 50.661821365356445 10.737022161483765 1.0 2010.08.07 17:32:39
GPS 16.0 50.66170871257782 10.737043619155884 1.8200275 2010.08.07 17:32:45
GPS 24.0 50.661579966545105 10.737027525901794 1.25 2010.08.07 17:32:50
GPS 16.0 50.66150486469269 10.73712408542633 1.0 2010.08.07 17:32:55
GPS 12.0 50.661579966545105 10.73715090751648 0.9013878 2010.08.07 17:33:01
GPS 24.0 50.66139221191406 10.737038254737854 1.5811388 2010.08.07 17:33:06
GPS 16.0 50.66141366958618 10.737301111221313 0.70710677 2010.08.07 17:33:12
GPS 16.0 50.66141366958618 10.737301111221313 0.70710677 2010.08.07 17:33:12
GPS 24.0 50.661311745643616 10.737070441246033 1.118034 2010.08.07 17:33:16
GPS 16.0 50.66122591495514 10.737177729606628 1.118034 2010.08.07 17:33:22
GPS 12.0 50.66124200820923 10.737220644950867 1.3462912 2010.08.07 17:33:26
GPS 12.0 50.661311745643616 10.737268924713135 3.6055512 2010.08.07 17:33:25
And so on... then another set of updates 2 minutes later at 17:35.
Is this the standard behavior? I was expecting to get only one location every 2 minutes, and the timespan in which it gives me location updates seems rather random. Ideally I would prefer to only get one location... is there a way to do this?
From the documentation of requestLocationUpdates(String provider, long minTime, float minDistance, LocationListener listener) concering the minTime parameter:
"the minimum time interval for notifications, in milliseconds. This field is only used as a hint to conserve power, and actual time between location updates may be greater or lesser than this value."
So the answer to your questions, yes this is standard behavior and, no you cannot change this.
If this is a problem for you, you could ignore calls to the callback method if a certain amount of time hasn't passed.
I found this question because I had the same problem.
I believe I have the answer. The rapid updates are being fired because you have the meters parameter set to 0.
Change the meters parameter to something like 10 and it will only fire the LocationChanged event every 2 minutes IF your location changed by 10 or more.
Before I made this change, LocationChanged was firing multiple times a second. Now, it fires once. Then every 2 minutes, you will see the GPS icon on the status bar, but unless your location changed, the event doesn't fire.
I hope this helps. This is what fixed it for me. Didn't have to add any extra logic to prevent false fires.
this is my LocationListener implementation to filter out unnecessary onLocationChanged() events:
NOTE I use messages in my service.
public class GPSlocationListener implements LocationListener
{
//member variables
private Handler mParentHandler;//points to Handler of parent
private long mTimeBetweenLocationEvents;
private long mTimeOfLastLocationEvent;
private boolean mAccuracyOverride;
private float mLastAccuracy;
private boolean mOverrideLocation;
//constants
private static final float INVALID_ACCURACY = 999999.0f;
private static final String TAG = "GPSlocationListener";
//constructor
public GPSlocationListener(Handler parentMsgHandler, long timeBetweenLocationEvents, boolean accuracyOverride)
{
mParentHandler = parentMsgHandler;
mTimeOfLastLocationEvent = 0;
mAccuracyOverride = accuracyOverride;
mLastAccuracy = INVALID_ACCURACY;
mOverrideLocation = false;
mTimeBetweenLocationEvents = timeBetweenLocationEvents;
}
//EVENT: onLocationChanged()
// send GPS coordinates to CommService
public void onLocationChanged(Location loc)
{
Log.d(TAG, "onLocationChanged() triggered. Accuracy = "+Float.toString(loc.getAccuracy()));
mOverrideLocation = false;
if (loc != null)
{
//if a more accurate coordinate is available within a set of events, then use it (if enabled by programmer)
if (mAccuracyOverride == true)
{
//whenever the expected time period is reached invalidate the last known accuracy
// so that we don't just receive better and better accuracy and eventually risk receiving
// only minimal locations
if (loc.getTime() - mTimeOfLastLocationEvent >= mTimeBetweenLocationEvents)
{
mLastAccuracy = INVALID_ACCURACY;
}
if (loc.hasAccuracy())
{
final float fCurrentAccuracy = loc.getAccuracy();
//the '<' is important here to filter out equal accuracies !
if ((fCurrentAccuracy != 0.0f) && (fCurrentAccuracy < mLastAccuracy))
{
mOverrideLocation = true;
mLastAccuracy = fCurrentAccuracy;
}
}
}
//ensure that we don't get a lot of events
// or if enabled, only get more accurate events within mTimeBetweenLocationEvents
if ( (loc.getTime() - mTimeOfLastLocationEvent >= mTimeBetweenLocationEvents)
||(mOverrideLocation == true) )
{
//be sure to store the time of receiving this event !
mTimeOfLastLocationEvent = loc.getTime();
//send message to parent containing the location object
Message msgToMain = mParentHandler.obtainMessage();
msgToMain.what = Constants.MSG_LOCATION_CHANGED;
msgToMain.obj = loc;
mParentHandler.sendMessage(msgToMain);
}
}
}
public void onProviderDisabled(String provider)
{
// TODO Auto-generated method stub
}
public void onProviderEnabled(String provider)
{
// TODO Auto-generated method stub
}
public void onStatusChanged(String provider, int status, Bundle extras)
{
// TODO Auto-generated method stub
}
}
this is implemented as follows in your main code:
//create the APIthread (which exposes mAPIhandler back to this service)
mAPIthread = new APIthread(mApiHandler);
mAPIthread.start();
//use the LocationManager class to obtain GPS locations
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
locationListener = new GPSlocationListener(mApiHandler, Constants.LOCATION_UPDATE_PERIOD_MSEC, true);
//this will call GPSlocationListener.onLocationChanged()
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,
//3 mins NOTE: approximate value
Constants.LOCATION_UPDATE_PERIOD_MSEC,
//no distance updates desired
0,
locationListener);