How can stop onLocationChanged() method using button click?
<p>I'm beginner for android development.I use Gps service implementing LocationListener.I want to stop onLocationChanged() method using button click.
I'm try to do this assigning null value to locationManager variable but it doesn't work it.</p>

<pre><code>public class TabFragment1 extends Fragment implements LocationListener {
    ImageButton btnRUN;
    ImageButton btnSTOP;
    private LocationManager locationManager;
    Context ctx;
    private double lat_new, lon_new = 0.0;


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        ctx = container.getContext();
        View view = inflater.inflate(R.layout.tab_fragment_1, container, false);

        initializeApp(view);
        return view;
    }


    private void initializeApp(View view) {
        btnRUN = (ImageButton) view.findViewById(R.id.btnRun);
        btnSTOP= (ImageButton) view.findViewById(R.id.btnStop);


        btnRUN.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                runOnClick();
            }
        });

        btnSTOP.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                stopOnClick();

            }
        });

    }
    public void stopOnClick(){
          locationManager =null;
    }

    public void runOnClick() {



        locationManager = (LocationManager) ctx.getSystemService(Context.LOCATION_SERVICE);
        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 3000, 10, this);


    }


    @Override
    public void onLocationChanged(Location location) {
        lat_new=location.getLatitude();
        lon_new=location.getLongitude();



        String str="Lat :"+lat_new +"Lon :"+lon_new;
        Toast.makeText(ctx,str,Toast.LENGTH_LONG).show();
    }

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

    }

    @Override
    public void onProviderEnabled(String provider) {
        Toast.makeText(ctx, "Gps turned on ", Toast.LENGTH_LONG).show();
    }

    @Override
    public void onProviderDisabled(String provider) {
        Toast.makeText(ctx, "Gps turned off ", Toast.LENGTH_LONG).show();
    }


} 
</code></pre>