CODEWITHSUNDEEP
androidgpsnullpointerexception
gkris
gkris

Reputation: 1219

Android GPS not working

I get a NullPointerException everytime i run the code. I have the Internet and GPS permissions (ACCESS_FINE_LOCATION, ACCESS_MOCK_LOCATION, & ACCESS_COARSE_LOCATION) enabled in the code. I have tried with both emulator and phone, both fails. It is not a problem of unavailable GPS or Internet, AFAIK.

My code snippet:-

@Override
public void onCreate (Bundle savedInstanceState) 
{
    try {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    mapView = (MapView) findViewById(R.id.mapView);
    LinearLayout zoomLayout = (LinearLayout)findViewById(R.id.zoom);  
    View zoomView = mapView.getZoomControls(); 

    zoomLayout.addView(zoomView, 
        new LinearLayout.LayoutParams(
            LayoutParams.WRAP_CONTENT, 
            LayoutParams.WRAP_CONTENT)); 
    mapView.displayZoomControls(true);
    mapView.setStreetView(false);
    mapView.setSatellite(false);

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

    locationManager.requestLocationUpdates(
            LocationManager.GPS_PROVIDER, 
            MINIMUM_TIME_BETWEEN_UPDATES, 
            MINIMUM_DISTANCE_CHANGE_FOR_UPDATES,
            new MyLocationListener()
    );

    mc = mapView.getController();
    //        String coordinates[] = {"51.708945", "8.745928"};  //THIS WORKS IF ENABLED
    //        double lat = Double.parseDouble(coordinates[0]);
    //        double lng = Double.parseDouble(coordinates[1]);


    Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
    double lat = location.getLatitude(); //NULLPOINTER EXCEPTION THROWN HERE
    double lng = location.getLongitude();

    p = new GeoPoint(
        (int) (lat * 1E6), 
        (int) (lng * 1E6)); 

    mc.animateTo(p);
    mc.setZoom(17); 
    //---Add a location marker---
    MapOverlay mapOverlay = new MapOverlay();
    List<Overlay> listOfOverlays = mapView.getOverlays();
    listOfOverlays.clear();
    listOfOverlays.add(mapOverlay);     

    mapView.invalidate();
    } catch (Exception e) {}
}

It throws NullPointer Exception when i am trying to get the latitude or the longitude. How do I avoid it? The locationManager object does not throw any exception on creation (using getSystemService method) nor does it give any exception when requesting location updates. I can check if the object is null before using it, but i dont understand why does it null at that point...is it worth putting a sleep? would that be the right way of programming? I dont understand why it doesnt work when i try to get the longitude/latitude. Am i doing something wrong?

Problems addressed here, or here or here could not solve my issue. Thank you.

Upvotes: 0

Views: 1340

Answers (1)

CaseyB
CaseyB

Reputation: 25060

I would say that mostly likely problem is that the LocationManager doesn't have a last known location so it's returning null. In that case you'll need to wait for a location update to get the position.

-= Update =- Just do this:

public void onLocationChanged(Location location) {
    double lat = location.getLatitude();
    double lng = location.getLongitude();

    p = new GeoPoint(
        (int) (lat * 1E6), 
        (int) (lng * 1E6)); 

    mc.animateTo(p);
    mc.setZoom(17);
}

Since this is an internal class it has access to all of your Activity members.

Upvotes: 1

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