问从未调用过onLocationChanged()

EN

public class FindLocation {
private LocationManager locManager;
private LocationListener locListener;
private Location mobileLocation;
private String provider;

public FindLocation(Context ctx){
    locManager = (LocationManager) ctx.getSystemService(Context.LOCATION_SERVICE);
    locListener = new LocationListener() {
        @Override
        public void onStatusChanged(String provider, int status,
                Bundle extras) {
        }
        @Override
        public void onProviderEnabled(String provider) {
        }
        @Override
        public void onProviderDisabled(String provider) {
        }
        @Override
        public void onLocationChanged(Location location) {
            System.out.println("mobile location is in listener="+location);
            mobileLocation = location;
        }
    };
    locManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 1, locListener);              
    if (mobileLocation != null) {
        locManager.removeUpdates(locListener); 
        String londitude = "Londitude: " + mobileLocation.getLongitude();
        String latitude = "Latitude: " + mobileLocation.getLatitude();
        String altitiude = "Altitiude: " + mobileLocation.getAltitude();
        String accuracy = "Accuracy: " + mobileLocation.getAccuracy();
        String time = "Time: " + mobileLocation.getTime();
        Toast.makeText(ctx, "Latitude is = "+latitude +"Longitude is ="+londitude, Toast.LENGTH_LONG).show();
    } else {
        System.out.println("in find location 4");
        Toast.makeText(ctx, "Sorry location is not determined", Toast.LENGTH_LONG).show();
    }
}
   }