Question

I need to show my current location as the Marker always on the Google Map using ItemizedOverlay but whenever I run the below code, my marker doesn’t showed up if I change the location from DDMS. Below is my code. Is there anything wrong I am doing?

public class MainActivity extends MapActivity {
    private MyItemizedOverlay myItemizedOverlay = null;
    private LocationManager locationManager = null;
    private MapView mapView = null;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mapView = (MapView) findViewById(R.id.mapView);
        mapView.setBuiltInZoomControls(true);

        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0,
                0, new GeoUpdateHandler());

    }


    public class GeoUpdateHandler implements LocationListener {

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

        Drawable marker=getResources().getDrawable(android.R.drawable.star_big_on);
        int markerWidth = marker.getIntrinsicWidth();
        int markerHeight = marker.getIntrinsicHeight();
        marker.setBounds(0, markerHeight, markerWidth, 0);


        myItemizedOverlay = new MyItemizedOverlay(marker);
        mapView.getOverlays().add(myItemizedOverlay);


        GeoPoint point = new GeoPoint(lat, lng);

        //GeoPoint myPoint1 = new GeoPoint((int) (37.347184*1000000), (int) (-121.966551*1000000));
        myItemizedOverlay.addItem(point, "myPoint1", "myPoint1");
        mapController.animateTo(point);
        String address = ConvertPointToLocation(point);
        Toast.makeText(getBaseContext(), address, Toast.LENGTH_SHORT).show();

        mapView.invalidate();

    }


}

Below is MyItemizedOverlay class

public class MyItemizedOverlay extends ItemizedOverlay<OverlayItem>{

    private ArrayList<OverlayItem> overlayItemList = new ArrayList<OverlayItem>();

    public MyItemizedOverlay(Drawable marker) {
        super(boundCenterBottom(marker));
        // TODO Auto-generated constructor stub

        populate();
    }

    public void addItem(GeoPoint p, String title, String snippet){
        OverlayItem newItem = new OverlayItem(p, title, snippet);
        overlayItemList.add(newItem);
        populate();
    }

    @Override
    protected OverlayItem createItem(int i) {
        // TODO Auto-generated method stub
        return overlayItemList.get(i);
    }

    @Override
    public int size() {
        // TODO Auto-generated method stub
        return overlayItemList.size();
    }

    @Override
    public void draw(Canvas canvas, MapView mapView, boolean shadow) {
        // TODO Auto-generated method stub
        super.draw(canvas, mapView, shadow);
        //boundCenterBottom(marker);
    }

}

As I need to show other Marker’s also on the Google Maps, so that is the reason I was going with ItemizedOverlay concept. Firstly I need to focus on my current location always using ItemizedOverlay whenever my app starts. Any suggestions on my example will be appreciated.

Answer 1

If all you want to do is display the user’s current location, then use MyLocationOverlay. It is specifically designed for this. Here is a good example on how to use it, and below is the basic central code snippet:

// This goes into the onCreate method
myLocationOverlay = new MyLocationOverlay(this, mapView);
mapView.getOverlays().add(myLocationOverlay);

myLocationOverlay.runOnFirstFix(new Runnable() {
  public void run() {
    mapView.getController().animateTo(myLocationOverlay.getMyLocation());
     }
}); 

See the tutorial for a more detailed example.