Question

I’m trying to create an application that uses OSMDroid and mapoverlays with geoPoints from the xml file, but i have a problem. Code editor doesn’t show me an error or warning but when i run the application in emulator it shows that application has stopped working.
This the code of mapActivity:

 public class MapsActivity extends Activity implements LocationListener, MapViewConstants {

    private MapView mapView;
    private MapController mapController;
    private LocationManager mLocMgr;
    static final String URL = "data/data/com.siroki.brijeg/data.xml";
    // XML node keys
    static final String KEY_ITEM = "object"; // parent node
    static final String KEY_ID = "id";
    static final String KEY_NAME = "name";
    static final String KEY_LON = "lon";
    static final String KEY_LAT = "lat";
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.copymain);

        mapView = (MapView) this.findViewById(R.id.mapview);
        mapView.setTileSource(TileSourceFactory.MAPNIK);
        mapView.setBuiltInZoomControls(true);
        mapView.setMultiTouchControls(true);

        mapController = this.mapView.getController();
        mapController.setZoom(14);
        GeoPoint point2 = new GeoPoint(43.3803,  17.5981);
        mapController.setCenter(point2);
        mLocMgr = (LocationManager) getSystemService(LOCATION_SERVICE);
        mLocMgr.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 100, this);

        mapView.invalidate();

        List<Overlay> mapOverlays = mapView.getOverlays();
        Drawable marker = this.getResources().getDrawable(R.drawable.ic_launcher);
        ObjectsOverlay itemizedOverlay = new ObjectsOverlay(marker, null);

        ArrayList<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>();

        XMLParser parser = new XMLParser();

        String xml = parser.getXmlFromUrl(URL); 
        Document doc = parser.getDomElement(xml); // getting DOM element

        NodeList nl = doc.getElementsByTagName(KEY_ITEM);



        // looping through all item nodes <item>
        for (int i = 0; i < nl.getLength(); i++) {
            // creating new HashMap
            HashMap<String, String> map = new HashMap<String, String>();
            Element e = (Element) nl.item(i);
            // adding each child node to HashMap key => value
            map.put(KEY_ID, parser.getValue(e, KEY_ID));
            map.put(KEY_NAME, parser.getValue(e, KEY_NAME));
            map.put(KEY_LON, "Rs." + parser.getValue(e, KEY_LON));
            map.put(KEY_LAT, parser.getValue(e, KEY_LAT));

            // adding HashList to ArrayList
            menuItems.add(map);
            GeoPoint geo = new GeoPoint(Double.parseDouble(parser.getValue(e, KEY_LAT)), Double.parseDouble(parser.getValue(e, KEY_LON)));
            OverlayItem overlayitem = new OverlayItem("Hellow", "World", geo);
            itemizedOverlay.addOverlay(overlayitem);
            mapOverlays.add(itemizedOverlay);

        }

    }

    public void onLocationChanged(Location location) {
        double lat = 43.3803;
        double lng = 17.5981 ;
        GeoPoint gpt = new GeoPoint(lat, lng);
        mapController.setCenter(gpt);
        mapView.invalidate();
    }

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

    }

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

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }



     }

ObjectsOverlay.java :

public class ObjectsOverlay extends ItemizedOverlay<OverlayItem> {



    public ObjectsOverlay(Drawable pDefaultMarker, ResourceProxy pResourceProxy) {
        super(pDefaultMarker, pResourceProxy);
        // TODO Auto-generated constructor stub
    }


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

    private Context context;



    @Override
       protected OverlayItem createItem(int i) {
          return mapOverlays.get(i);
       }

       @Override
       public int size() {
          return mapOverlays.size();
       }

       protected boolean onTap(int index) {
          OverlayItem item = mapOverlays.get(index);
          AlertDialog.Builder dialog = new AlertDialog.Builder(context);
          dialog.setTitle(item.getTitle());
          dialog.setMessage(item.getSnippet());
          dialog.show();
          return true;
       }

       public void addOverlay(OverlayItem overlay) {
          mapOverlays.add(overlay);
           this.populate();
       }

    @Override
    public boolean onSnapToItem(int arg0, int arg1, Point arg2, IMapView arg3) {
        // TODO Auto-generated method stub
        return false;
    }

}

And XML file data.xml:

<?xml version="1.0" encoding="UTF-8"?>

<objects>

    <object>
        <id>1</id>    

        <name>Siroki</name>

        <lon>17.602985</lon>

        <lat>43.374276</lat>
    </object> 
</objects>

I didn’t wrote the imports code becouse they take alot of space. 😀

Answer 1

First, the context defined in your ObjectsOverlay is never being set. You should add a Context parameter in the constructor:

public ObjectsOverlay(Drawable pDefaultMarker, ResourceProxy pResourceProxy, Context context) {
        super(pDefaultMarker, pResourceProxy);
        this.context = context;
    }

so that the DialogBuilder used in onTap can have a context to create the dialog on. Without this your app will most probably crash when tapping an item.

Next, you wrongly initialized the GeoPoint, it should be done like this:

GeoPoint point = new GeoPoint(19240000,-99120000);
OverlayItem overlayitem = new OverlayItem(point, "Hola, Mundo!", "I'm in Mexico City!");

GeoPoint coordinates are not double, like Location coordinates. They are int equal to coordinate * 1E6. Use it like this:

int lon = (int)Math.round(lon_as_double*1E6)

And the last thing, you do

itemizedOverlay.addOverlay(overlayitem);
mapOverlays.add(itemizedOverlay);

in the same for-loop. But you should actually just addOverlay in the loop, where you add one by one object by its coordinates, and add the complete itemizedOverlay to the map after the loop.
Oh and you could also add the overlay at the beginning (before the loop), and then populate it using addOverlay. The order does not matter, it only matters to add the overlay once with mapOverlays.add.

Fix that and see if errors still happen.

Regards.