Ошибка в определении местоположения

import android.Manifest;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.support.v4.content.ContextCompat;
 
 
public class GPSTracker extends Service implements LocationListener {
 
    private final Context context;
 
    boolean isGPSEnabled=false;
    boolean isNetworkEnabled=false;
 
    Location location;
    protected LocationManager locationManager;
 
    public GPSTracker(Context context) {
        this.context = context;
    }
 
    public Location getLocation(){
        try{
            locationManager=(LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
            isGPSEnabled = locationManager.isProviderEnabled((locationManager.GPS_PROVIDER));
            isNetworkEnabled=locationManager.isProviderEnabled(locationManager.NETWORK_PROVIDER);
 
            
            if(ContextCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
                    || ContextCompat.checkSelfPermission(context, Manifest.permission.ACCESS_COARSE_LOCATION)==PackageManager.PERMISSION_GRANTED){
 
                if(isGPSEnabled){
                    if(location==null){
                        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,10000,10,this);
                        if(locationManager!=null){
                            location=locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        }
                    }
                }
                if(location==null){
                    if(isNetworkEnabled){
                        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,10000,10,this);
                        if(locationManager!=null){
                            location=locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        }
                    }
                }
 
            }
 
        } catch (Exception ex){
 
        }
        return location;
    }
 
    @Override
    public void onLocationChanged(Location location) {
 
    }
 
    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
 
    }
 
    @Override
    public void onProviderEnabled(String provider) {
 
    }
 
    @Override
    public void onProviderDisabled(String provider) {
 
    }
 
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}
 
 
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
 
    private GoogleMap mMap;
 
    private  GPSTracker gpsTrack;
    private  Location mLocation;
    double latitude, longt;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
 
        gpsTrack = new GPSTracker(this);
        mLocation=gpsTrack.getLocation();
 
        latitude=mLocation.getLatitude();
        longt=mLocation.getLongitude();
      
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);        
        mapFragment.getMapAsync(this); 
 
            
 
    }
 
    @Override
    public void onMapReady(GoogleMap googleMap) {
 
        LatLng marker = new LatLng(latitude, longt);
        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(marker));
 
    }
 
 
}