ItemizedOverlay 崩溃问题

Question

我已经尝试了几个小时来弄清楚为什么在将逐项地图叠加添加到地图的叠加之前，我不能不这样做就不能使用它：

GeoPoint point; OverlayItem overlayitem = new OverlayItem(point, "",""); MarkerOverlay.addOverlay(overlayitem);

如果我尝试在没有MarkerOverlay.addOverlay(overlayitem); 命令的情况下执行此操作，那么当我尝试像这样添加新的覆盖时：

public boolean onTap(GeoPoint point, MapView mapView)
{
    if (mOverlays.size() > 0)
        mOverlays.remove(0);
    OverlayItem overlayitem = new OverlayItem(point, "", "");
    mOverlays.add(overlay);
    populate();
    return true;
}

在我的 ItemizedOverlay 类中，我只得到一个空引用异常（我不知道何时或为什么 - 它说它在调试时没有可用的源代码）

有什么想法吗？

编辑： 这是我可以在 logcat 中找到的：

09-20 22:36:22.164: WARN/dalvikvm(311): threadid=3: thread exiting with uncaught exception (group=0x4001b188)

这就是我认为臭名昭著的例外：

   09-20 22:36:22.293: ERROR/AndroidRuntime(311): java.lang.NullPointerException
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.google.android.maps.ItemizedOverlay.getItemsAtLocation(ItemizedOverlay.java:617)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.google.android.maps.ItemizedOverlay.getItemAtLocation(ItemizedOverlay.java:586)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.google.android.maps.ItemizedOverlay.handleMotionEvent(ItemizedOverlay.java:498)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.google.android.maps.ItemizedOverlay.onTouchEvent(ItemizedOverlay.java:572)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.google.android.maps.OverlayBundle.onTouchEvent(OverlayBundle.java:63)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.google.android.maps.MapView.onTouchEvent(MapView.java:625)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at android.view.View.dispatchTouchEvent(View.java:3709)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:852)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:822)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:822)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:822)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1659)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at android.app.Activity.dispatchTouchEvent(Activity.java:2061)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1691)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at android.os.Looper.loop(Looper.java:123)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at android.app.ActivityThread.main(ActivityThread.java:4363)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at java.lang.reflect.Method.invokeNative(Native Method)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at java.lang.reflect.Method.invoke(Method.java:521)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
09-20 22:36:22.293: ERROR/AndroidRuntime(311):     at dalvik.system.NativeStart.main(Native Method)
09-20 22:36:22.394: ERROR/dalvikvm(311): Unable to open stack trace file '/data/anr/traces.txt': Permission denied

Answer 1

我最近遇到了这个问题。此bug report 中概述了该问题。

要修复它，您应该在填充任何数据之前在 ItemizedOverlay 中调用 populate()。我将它添加到构造函数中：

private class MyItemizedOverlay extends ItemizedOverlay<OverlayItem> {

    private Context context;
    private ArrayList<OverlayItem> mOverlays = new ArrayList<OverlayItem>();

    LocationItemizedOverlay(Drawable defaultMarker, Context context) {
        super(boundCenterBottom(defaultMarker));
        this.context = context;
        populate(); // Add this
    }
}

Answer 2

逐项叠加需要第二个 2 参数，因为它将它们用于点击事件。当您单击其中一个逐项叠加时，它具有与之关联的标题和描述，它们是叠加项中的第二个和第三个参数

Answer 3

如果您对 ItemizedOverlay 进行了重要更改，那么您每次都可以做

1. delete_usrer_Marker_from_Overlays(myitemizedoverlay);
2. create_user_Marker(myitemizedoverlay);
3. mapView.getOverlays().add(myitemizedoverlay);

与

private void delete_usrer_Marker_from_Overlays(MyOverlays myio){

    List<Overlay> mapOverlays = mapView.getOverlays();
    if (mapOverlays != null) 
        {
          for (int i = 0;i< mapOverlays.size();i++)
          {
              Overlay x = mapOverlays.get(i);
              if (x.hashCode() == myio.hashCode())
              {
                  mapOverlays.remove(x);
              }                     
          }
        }       
    }