Question

我有一张带有自定义叠加层和一堆标记的地图。因为当缩放发生变化时我正在进行标记分组，我必须清除叠加，重新组合项目以进行新的缩放，然后再次放置在地图上。我在背景线程中这样做以使事情顺利进行。因此，您单击缩放，标记消失，繁忙指示符显示在角落，新标记显示在地图上。一切都很平滑，但是当你在行中放大两倍或放大并立即缩小时，我会得到一致的修改异常。我已经阅读了很多关于此的内容，但我还没有解决方案。例如，将地图移动到UI上的onPostExecute确实可以防止这种情况，但是会冻结地图以绘制时间标记并且它会失去平滑性。我试图在逐项列表同步列表上制作标记列表，但没有帮助。我该如何防止这种情况？

这就是我对变焦更改的要求：

private void drawItems() {
  final MyMapView mw = this.mapView;

  //remove existing first
  //mw.getOverlays().remove(stuffOverlay);
  stuffOverlay.clearAll();
  //mw.invalidate();

  new AsyncTask<String, Integer, String>() {
    @Override
    protected void onPreExecute() {
      super.onPreExecute();
      ((ProgressBar)findViewById(R.id.mapProgressBar)).setVisibility(View.VISIBLE);
    }

    @Override
    protected String doInBackground(String... params) {
      //get items on map
      HashMap<String, JSONArray> groupedItems = getItemsForZoom(mw.getZoomLevel());

      if (groupedItems==null)
        return "done";

      //create a copy of it sometimes it was throwing concurentmodificationexception
      HashMap<String, JSONArray> groupedItemsCopy = new HashMap<String, JSONArray> (groupedItems);

      Iterator it = groupedItemsCopy.entrySet().iterator();
      while (it.hasNext()) { //loop over markers
        try {
          //get item 
          HashMap.Entry<String, Object> pair = (HashMap.Entry)it.next();
          JSONArray itemsInMarker = (JSONArray) pair.getValue();
          JSONObject itemData = (JSONObject) itemsInMarker.get(0);

          //get truncated coordinates
          String coordsKey = pair.getKey();
          String[] coordsSplitted = coordsKey.split("_");

          //add first marker to map
          GeoPoint gp = new GeoPoint((int)(Double.parseDouble(coordsSplitted[0])*1E6), (int)(Double.parseDouble(coordsSplitted[1])*1E6));
          OverlayItem markerOverlay = new OverlayItem(gp, "marker", "snipper text");
          Drawable markerPic = ServerCall.drawableFromUrl(((JSONObject)((JSONObject)itemData.get("picture")).get("1")).get("picture_full")+"_0.png");
          //markerPic.setBounds(0, 0, markerPic.getIntrinsicWidth(), markerPic.getIntrinsicHeight());
          markerPic.setBounds(-25, -25, 50, 50);
          markerOverlay.setMarker(markerPic);
          stuffOverlay.addOverlay(markerOverlay, itemData);

          if (stuffOverlay.size() > 0) {
            mapView.getOverlays().add(stuffOverlay);
          }
        } catch (JSONException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      return "done";
    }

    @Override
    protected void onPostExecute(String result) {
      super.onPostExecute(result);
      ((ProgressBar)findViewById(R.id.mapProgressBar)).setVisibility(View.GONE);
      mapView.invalidate();
    }
  }.execute();
}

这是我的逐项清单：

private class StuffOverlay extends ItemizedOverlay {
  private List<OverlayItem> mOverlays = Collections.synchronizedList(new ArrayList<OverlayItem>());
  private ArrayList<JSONObject> mStuff = new ArrayList<JSONObject>();
  public int currentItem;
  Map mMap;

  public StuffOverlay(Drawable defaultMarker, Map map) {
    super(boundCenterBottom(defaultMarker));
    mMap = map;
    populate(); //keep here
  }

  public void addOverlay(OverlayItem overlay, JSONObject stuffData) {
    synchronized (mOverlays) {
      mOverlays.add(overlay);
    }

    mStuff.add(stuffData);
    setLastFocusedIndex(-1);  //keep here
    populate();
  }

  public void clearAll() {
    synchronized (mOverlays) {
      mOverlays.clear();
    }

    setLastFocusedIndex(-1); //keep here
    populate();
  }

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

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

  public void draw(Canvas canvas, MapView mapView, boolean shadow) {
    if (!shadow) {
      super.draw(canvas, mapView, false);
    }
  }
}

这就是我所得到的; o（

05-30 20:45:35.485: W/dalvikvm(1139): threadid=3: thread exiting with uncaught exception (group=0x4001b188)
05-30 20:45:35.485: E/AndroidRuntime(1139): Uncaught handler: thread main exiting due to uncaught exception
05-30 20:45:35.495: E/AndroidRuntime(1139): java.util.ConcurrentModificationException
05-30 20:45:35.495: E/AndroidRuntime(1139):     at java.util.AbstractList$SimpleListIterator.next(AbstractList.java:64)
05-30 20:45:35.495: E/AndroidRuntime(1139):     at com.google.android.maps.OverlayBundle.draw(OverlayBundle.java:44)
05-30 20:45:35.495: E/AndroidRuntime(1139):     at com.google.android.maps.MapView.onDraw(MapView.java:476)
05-30 20:45:35.495: E/AndroidRuntime(1139):     at android.view.View.draw(View.java:6535)
05-30 20:45:35.495: E/AndroidRuntime(1139):     at android.view.ViewGroup.drawChild(ViewGroup.java:1531)
05-30 20:45:35.495: E/AndroidRuntime(1139):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1258)

Answer 1

我认为这个问题可能与这些问题有关：

      if (stuffOverlay.size() > 0) {
        mapView.getOverlays().add(stuffOverlay);
      }

您只需要将对象stuffOverlay添加到地图叠加数组一次，您甚至可以在stuffOverlay中包含任何项目之前执行此操作。我会将mapView.getOverlays().add(stuffOverlay);移动到实例化stuffOverlay的位置。

Android maps itemizedoverlay ConcurrentModificationException

1 个答案: