@Override
       protected boolean onTap(int index) {

          OverlayItem item = mOverlays.get(index);


              if (null==item ) {
                  Toast.makeText(context,"it is null",Toast.LENGTH_LONG).show();
                  AlertDialog.Builder dialog = new AlertDialog.Builder(context);
                  dialog.setTitle("title");
                  dialog.setMessage("Message");
                  return true;
               }
               else {
                      AlertDialog.Builder dialog = new AlertDialog.Builder(context);
                      dialog.setTitle(item.getTitle());
                      dialog.setMessage(item.getSnippet());
                      dialog.show();
                      return true;
               }



       }