Как добавить маркер, когда я касаюсь карты в Android?

У меня есть активность карты, которая отображает карту, я хочу добавить маркер, когда касаюсь экрана.

Это моя активность...

package com.adhamenaya.android;

import java.util.List;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.view.MotionEvent;
import android.widget.Toast;

import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import com.google.android.maps.OverlayItem;

public class MapApp extends MapActivity {

    private MapView mapView;
    private MapController mapController;
    private LocationManager locationManager;
    private Context context;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        context=this;
        initLayout();
        initMap();
    }

    private void initLayout(){
         mapView = (MapView) findViewById(R.id.mapview);
         //blueIcon = (Drawable)this.getResources().getDrawable(R.drawable.blueicon);

    }
    private void initMap(){
        mapView.setBuiltInZoomControls(true);
        mapView.setStreetView(true);
        mapController=mapView.getController();
        mapController.setZoom(10);// 1 is world view
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,0, 0, new GeoUpdateHandler());

    }


    @Override
    protected boolean isRouteDisplayed() {
        // TODO Auto-generated method stub
        return false;
    }

    class GeoUpdateHandler implements LocationListener {

        @Override
        public void onLocationChanged(Location location) {
            int lat=(int)(location.getLatitude()*1E6);
            int lng=(int)(location.getLongitude()*1E6);

            GeoPoint point=new GeoPoint(lat,lng);
            //GeoPoint point = new GeoPoint(19240000,-99120000);

            mapController.animateTo(point);
            mapController.setCenter(point);
            Drawable redIcon = context.getResources().getDrawable(R.drawable.redicon);
            List<Overlay> mapOverlays = mapView.getOverlays();
            MyItemizedOverlay itemizedoverlay = new MyItemizedOverlay(redIcon);
            OverlayItem overlayitem = new OverlayItem(point, "Hello !", "I'm here");
            itemizedoverlay.addOverlay(overlayitem);
            mapOverlays.add(itemizedoverlay);
        }

        @Override
        public void onProviderDisabled(String arg0) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onProviderEnabled(String arg0) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
            // TODO Auto-generated method stub

        }
        public boolean onTouchEvent(MotionEvent event){
            int x=(int)event.getX();
            int y=(int)event.getY();
            Toast.makeText(context, x, Toast.LENGTH_LONG).show();
            GeoPoint point = mapView.getProjection().fromPixels(x, y);

            Drawable redIcon = context.getResources().getDrawable(R.drawable.blueicon);
            List<Overlay> mapOverlays = mapView.getOverlays();
            MyItemizedOverlay itemizedoverlay = new MyItemizedOverlay(redIcon);
            OverlayItem overlayitem = new OverlayItem(point, "New Place", "I clicked here !");
            itemizedoverlay.addOverlay(overlayitem);
            mapOverlays.add(itemizedoverlay);
            return false;
        }

}
}

Редактировать: это класс для ItemizedOverlay, где я реализовал метод onTap(), но ничего не происходит...

package com.adhamenaya.android;

import java.util.ArrayList;

import android.app.AlertDialog;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.view.MotionEvent;
import android.widget.Toast;

import com.google.android.maps.ItemizedOverlay;
import com.google.android.maps.MapView;
import com.google.android.maps.OverlayItem;

public class MyItemizedOverlay extends ItemizedOverlay{

    private ArrayList<OverlayItem> mOverlays = new ArrayList<OverlayItem>();
    private Context mContext;
    public MyItemizedOverlay(Drawable defaultMarker) {
          super(boundCenterBottom(defaultMarker));
    }

    public MyItemizedOverlay(Drawable defaultMarker, Context context) {
          super(defaultMarker);
          mContext = context;
    }
    public void addOverlay(OverlayItem overlay) {
        mOverlays.add(overlay);
        populate();
    }
    @Override
    protected OverlayItem createItem(int i) {
        return mOverlays.get(i);
    }
    @Override
    public int size() {
        return mOverlays.size();
    }
    @Override
    protected boolean onTap(int index) {
      OverlayItem item = mOverlays.get(index);
      AlertDialog.Builder dialog = new AlertDialog.Builder(mContext);
      dialog.setTitle(item.getTitle());
      dialog.setMessage(item.getSnippet());
      dialog.show();
      return true;
    }
     @Override
        public boolean onTouchEvent(MotionEvent event, MapView mapView) {
         int x=(int)event.getX();
            int y=(int)event.getY();
            Toast.makeText(mContext, x, Toast.LENGTH_LONG).show();
            return super.onTouchEvent(event, mapView);
        }


}