Question

In my app I am checking GPS strength. I get an java.lang.IllegalArgumentException:

listener==null.

I did not assign code listener to be null, and I write the code in the OnCreate() method. I don’t know why listener turns null. Where am I going wrong?

My code:

public class Gps_strength extends Activity{
    private LocationManager mLocationManager;
    private LocationListener mGpsLocationListener;
    private GpsStatus.Listener gps_listener;

    public void onCreate(Bundle savedInstanceState) {
        mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, mGpsLocationListener);  // line no 31.
        mLocationManager.addGpsStatusListener(gps_listener);
        if (mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER) == true) {
          ..... GPS strength checking coding..
        }
    }
}

Logcat:

    06-03 13:04:30.695: ERROR/AndroidRuntime(2595): Caused by:     java.lang.IllegalArgumentException: listener==null
    06-03 13:04:30.695: ERROR/AndroidRuntime(2595):     at android.location.LocationManager.requestLocationUpdates(LocationManager.java:627)
    06-03 13:04:30.695: ERROR/AndroidRuntime(2595):     at com.gps.Gps_strength.onCreate(Gps_strength.java:31)

Answer 1

You don’t appear to be ever setting mGpsLocationListener to equal anything.

---

Alter your declations to:

private LocationListener mGpsLocationListener = new LocationListener()
{

  public void onLocationChanged(Location arg0)
  {
  }

  public void onProviderDisabled(String provider)
  {
  }

  public void onProviderEnabled(String provider)
  {
  }

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

};

private GpsStatus.Listener gps_listener = new GpsStatus.Listener()
{
  public void onGpsStatusChanged(int event)
  {
  }
};