android - GpsStatus.Listener works only if GPS is on

Question

in my App I have a GpsStatus.Listener to receive events when the user enables or disables GPS. Everything works fine if GPS is on before I start the app. In this case I receive a GPS_EVENT_STARTED or a GPS_EVENT_STOPPED everytime I toggle GPS on or off.

The problem is if GPS is off while app is starting. In this case I don't receive an event if I toggle GPS on or off.

Can someone explain that to me?

Here is my code:

public class GPSTracker implements android.location.GpsStatus.Listener {

    private final Context context;
    private final LocationListener locListener;
    private LocationManager locationManager;
    private boolean isGPSEnabled = false;

    public GPSTracker(Context context, LocationListener locListener) {
            this.context = context;
            this.locListener = locListener; 
            setupGPS();
    }

    private void setupGPS() {
            locationManager = (LocationManager) getContext().getSystemService(Context.LOCATION_SERVICE);                
            locationManager.addGpsStatusListener(this);
            isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
            if(!isGPSEnabled) {
                    Toast.makeText(getContext(), "GPS disabled", Toast.LENGTH_SHORT).show();
            } else {        
                    locationManager.removeUpdates(locListener);
                    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, MIN_TIME, MIN_DISTANCE, locListener);
            }
    }

    @Override
    public void onGpsStatusChanged(int event) {
            Log.e("onGpsStatusChanged", event+""); 
            switch(event) {
            case GpsStatus.GPS_EVENT_STARTED:
                    Log.e("onGpsStatusChanged", "GPS_EVENT_STARTED");
                    break;
            case GpsStatus.GPS_EVENT_STOPPED:
                    Log.e("onGpsStatusChanged", "GPS_EVENT_STOPPED");
                    break;
            }
    }

So, my logcat output is (if GPS is on while starting):

• GpsStatusChanged(24638): 1 // app starts
• GpsStatusChanged(24638): GPS_EVENT_STARTED
• GpsStatusChanged(24638): 4 // searching for fixes
• GpsStatusChanged(24638): 4
• GpsStatusChanged(24638): 2 // toggle GPS off
• GpsStatusChanged(24638): GPS_EVENT_STOPED

Output with GPS off: nothing.

Answer 1

Well, LocationListener has been provided with:

onProviderDisabled(),onProviderEnabled() and onStatusChanged() for exactly this purpose.

GpsStatus.Listener delivers info about GPS service's inner workings. It is not to be used for telling the status pf GPS Provider.

LocationListener delivers info about providers. The moment you register LocationListener with location provider, onProviderEnabled()/onProviderDisabled() is called accordingly, and your app can always tell when GPS is turned on or off.

Try this:

public class test extends Activity implements LocationListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER,1000,10,this);
    }


    @Override
    public void onLocationChanged(Location location) {
    }

    @Override
    public void onStatusChanged(String s, int i, Bundle bundle) {
    }

    @Override
    public void onProviderEnabled(String s) {
        if(LocationManager.GPS_PROVIDER.equals(s)){
            Toast.makeText(this,"GPS on",Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    public void onProviderDisabled(String s) {
        if(LocationManager.GPS_PROVIDER.equals(s)){
            Toast.makeText(this,"GPS off",Toast.LENGTH_SHORT).show();
        }
    }
}