Question

我有以下代码从数据库获取信息并在地图上绘制。信息存在且可点击，但实际图标androidmarker不可见。为什么？我该如何解决这个问题？

public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    tweets = new LocationData(this);

    mapView = (MapView) findViewById(R.id.mapView);
    mapView.setSatellite(true);
    mc = mapView.getController();

    mc.setZoom(17);
    mapView.setBuiltInZoomControls(true);


    // Add the MyPositionOverlay
    positionOverlay = new MyPositionOverlay();
    List<Overlay> overlays = mapView.getOverlays();
    overlays.add(positionOverlay);

    //Add the Mapitems Overlay.

    mapOverlays = mapView.getOverlays();
    Drawable drawable = this.getResources().getDrawable(R.drawable.androidmarker);
    itemizedoverlay = new Mapitems(drawable, this);

    mylocation();
    distance(lat,lng);
    addmark();
    mapView.invalidate();
}

public void addmark(){

    SQLiteDatabase db = tweets.getWritableDatabase();
    String count = "SELECT * FROM tweets;";
    Cursor mcursor = db.rawQuery(count, null);
    startManagingCursor(mcursor);
    mcursor.moveToFirst();  
    if(mcursor != null && mcursor.moveToFirst())
    {
            do
            {
                System.out.println("WHAT");
            String tname = mcursor.getString(4);
            String tmessage = mcursor.getString(7);
            Double tlat = mcursor.getDouble(1);
            System.out.println("lat" + tlat);
            Double tlng = mcursor.getDouble(2);
            System.out.println("lng" + tlng);

            GeoPoint point = new GeoPoint(
                    (int) (tlat*1E6),
                    (int) (tlng*1E6));
            OverlayItem overlayitem = new OverlayItem(point, tname, tmessage);
            itemizedoverlay.addOverlay(overlayitem);
            mapOverlays.add(itemizedoverlay);


            }while(mcursor.moveToNext());

    }
}

Answer 1

我假设Mapitems是实现ItemizedOverlay的类。可能存在问题。您可以按照here的说明正确地创建该类。我自己也遵循了这个教程，它对我来说很好。重要的是确保在populate()

中添加叠加后调用addOverlay(OverlayItem overlay)

另外，为什么你有mapOverlays和overlays？他们不一样吗？

标记图标未显示但可点击

1 个答案: