Android - Google Maps - LocationListener - adding marker onLocationChanged makes app crash

Question

I want a marker to show my current location. All permissions needed are added. When I comment out mMap.addMarker and mMap.moveCamera the app is working and Googlemaps is shown. If I let one of those two in my code the app crashes before the map even opens.

I've tried with removing the marker if it isn't null but this doesn't solve the problem.

Do you guys have any idea how I can get the app working?

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, LocationListener {


private GoogleMap mMap;
private List<LatLng> fountain = null;
private LocationManager locationManager;
private double posLat;
private double posLng;

private LatLng position;
private Marker mPosition;


protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);

    locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
    startGPS();


}

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    // Add a marker in Sydney and move the camera
    LatLng sydney = new LatLng(48.16786112327462, 16.383984438313828);
    mPosition = mMap.addMarker(new MarkerOptions().position(sydney).title("Your Position").icon(BitmapDescriptorFactory.fromResource(R.drawable.location)));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));


}


//--------------------------------------------GPS Listener---------------------------------------
public void startGPS() {

    if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
            && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {

        ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION}, 5);
    }
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 3000, 5, this);
    onLocationChanged(locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER));

}

@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
        case 5: {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

            } else {
                getDialog2("Keine Erlaubnis für GPS").show();
            }
        }
    }
}


@Override
public void onLocationChanged(Location location) {
    posLat = location.getLatitude();
    posLng = location.getLongitude();

    position = new LatLng(posLat, posLng);

    if (mPosition != null) {
        mPosition.remove();
    }

    mPosition = mMap.addMarker(new MarkerOptions().position(position).title("Your position").
            icon(BitmapDescriptorFactory.fromResource(R.drawable.location)));
    mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(position, 11));

}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {

}

@Override
public void onProviderEnabled(String provider) {

}

@Override
public void onProviderDisabled(String provider) {

}

//----------------------------Helper Methods-----------------------------------------------

public Dialog getDialog2(String string) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage(string);
    builder.setPositiveButton("OK",
            new DialogInterface.OnClickListener() {
                @Override

                public void onClick(DialogInterface dialog, int which) {
                    finish();
                }
            });
    return builder.create();
}


public Dialog getDialog(String string) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage(string);
    builder.setPositiveButton("OK",
            new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                }
            });
    return builder.create();
}

}

Answer 1

Okay, I already solved the problem. So I post the solution here.

I have implemented on the MapsActivity the LocationListener interface and for some reason it doesn't work this way. I can retrieve the geocoordinates but as soon as I want to move the camera or add a marker it the app crashes as it gets opened.

I don't know why, but instead of:

locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 3000, 5, this)

I undo the implementation of the LocationListener and just create a new one at the position of ,,this":

locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 3000, 5, new LocationListener() {
                    @Override
                    public void onLocationChanged(Location location) {
                        posLat = location.getLatitude();
                        posLng = location.getLongitude();

                        position = new LatLng(posLat, posLng);

                        if (mPosition != null) {
                            mPosition.remove();
                        }

                        mPosition = mMap.addMarker(new MarkerOptions().position(position).title("Your position").
                                icon(BitmapDescriptorFactory.fromResource(R.drawable.location)));

                        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(position, 11));

                    }

                    @Override
                    public void onStatusChanged(String provider, int status, Bundle extras) {

                    }

                    @Override
                    public void onProviderEnabled(String provider) {

                    }

                    @Override
                    public void onProviderDisabled(String provider) {

                    }
                }


        );

and this way it works without problem.