访问更新列表视图的第一个元素会导致 System.ArgumentOutOfRangeException

Question

我更新列表，从中删除不需要的项目，然后调用 adapter.NotifyDataSetChanged。当我单击更新后的 ListView 中的第一个元素时，System.ArgumentOutOfRangeException 会弹出（这个元素似乎保留了它在更新之前在列表中的索引 ）。相反，当我单击更新后的列表视图中的其他项目时，没有问题。

List<Event> eventsToRemove = new List<Events>;

//Populating eventsToRemove with some "not-matching-some-criterion" <Event> instances taken from the original List<Event> events

for (var i = 0; i < eventsToRemove.Count; i++) {
                        events.Remove(eventsToRemove[i]);
}
adapter.NotifyDataSetChanged();

我猜问题出在更新适配器的线程和管理 UI 的线程上。我想解决这个问题：

Unhandled Exception:

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.

Parameter name: index

日志：

07-20 12:54:41.252 D/ViewRootImpl@3e1ee4d[Toast](18915): MSG_RESIZED_REPORT: ci=Rect(0, 0 - 0, 0) vi=Rect(0, 0 - 0, 0) or=1
07-20 12:54:41.667 D/ViewRootImpl@3e1ee4d[Toast](18915): mHardwareRenderer.destroy()#4
07-20 12:54:41.667 D/ViewRootImpl@5f20f01[MainActivity](18915): ViewPostImeInputStage processPointer 0
07-20 12:54:41.668 D/ViewRootImpl@3e1ee4d[Toast](18915): dispatchDetachedFromWindow
07-20 12:54:41.674 D/InputTransport(18915): Input channel destroyed: fd=75
07-20 12:54:41.716 D/ViewRootImpl@5f20f01[MainActivity](18915): ViewPostImeInputStage processPointer 1
07-20 12:54:42.057 D/Mono    (18915): Assembly Ref addref Mono.Android[0x73a4bea880] -> System.Runtime.Serialization[0x738f4cf780]: 3
Unhandled Exception:

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index

Thread finished: <Thread Pool> #10
Il thread 0xa è terminato con il codice 0 (0x0).
Thread finished: <Thread Pool> #5
Il thread 0x5 è terminato con il codice 0 (0x0).
Thread finished: <Thread Pool> #12
Il thread 0xc è terminato con il codice 0 (0x0).
Thread finished: <Thread Pool> #6
Il thread 0x6 è terminato con il codice 0 (0x0).
Thread finished: <Thread Pool> #11
Il thread 0xb è terminato con il codice 0 (0x0).

Github 链接及相应代码：https://github.com/eddybudge/PerugiaEventi1/blob/master/PerugiaEventi1/MainActivity.cs

另外，当我点击更新列表的第一个元素时，我会在控制台上得到以下输出：

[0:] Position: 0 Number of elements inside the list: 9
[0:] Position: 1 Number of elements inside the list: 9
[0:] Position: 2 Number of elements inside the list: 9
[0:] Position: 3 Number of elements inside the list: 9
[0:] Position: 4 Number of elements inside the list: 9
[0:] Position: 5 Number of elements inside the list: 9
[0:] Position: 6 Number of elements inside the list: 9
[0:] Position: 7 Number of elements inside the list: 9
[0:] Position: 8 Number of elements inside the list: 9
[0:] Position: 9 Number of elements inside the list: 9

，而 当我点击任何其他按钮时，我会得到

[0:] Position: x Number of elements inside the list: y

• 这很奇怪，因为应该只打印一行！！！

（我每次点击按钮时都使用System.Diagnostics.Debug.WriteLine("Position: "+position+" Number of elements inside the list: "+eventi.Count());）

更新：

最后我决定捕获异常并使用内部捕获0作为索引 - 因为在测试期间它始终是导致问题的第一个元素。 顺便说一句，我没有找到问题的核心 - 这就是造成问题的原因和原因。

Answer 1

关于这个问题

此外，当我单击更新列表的第一个元素时，我会得到 控制台上的以下输出

[0:] Position: 0 Number of elements inside the list: 9
[0:] Position: 1 Number of elements inside the list: 9
[0:] Position: 2 Number of elements inside the list: 9
[0:] Position: 3 Number of elements inside the list: 9
[0:] Position: 4 Number of elements inside the list: 9
[0:] Position: 5 Number of elements inside the list: 9
[0:] Position: 6 Number of elements inside the list: 9
[0:] Position: 7 Number of elements inside the list: 9
[0:] Position: 8 Number of elements inside the list: 9
[0:] Position: 9 Number of elements inside the list: 9

你只需要添加以下代码

 if (!bottoneEvento.HasOnClickListeners) {
 }

如下：

public override View GetView(int position, View convertView, ViewGroup parent)
    {
        var view = convertView ?? activity.LayoutInflater.Inflate(Resource.Layout.list_item, parent, false);
        var bottoneEvento = view.FindViewById<Button>(Resource.Id.bottoneEventAdapter);

        bottoneEvento.Text = eventi[position].Titolo;
        //bottoneEvento.Tag = position;  --forse non serve
        if (!bottoneEvento.HasOnClickListeners)  // key code
        {
            bottoneEvento.Click += (sender, args) =>
          {
            System.Diagnostics.Debug.WriteLine("Position: "+position+" Number of elements inside the list: "+eventi.Count());
            //bisogna, immagino fare l'update della view con notify - prima creando un observer.
            Intent dettagli = new Intent(Application.Context, typeof(EventoInDettaglio));
            dettagli.PutExtra("titolo", bottoneEvento.Text);
            dettagli.PutExtra("url", eventi[position].Url);
            dettagli.PutExtra("inizia", eventi[position].Inizio);
            dettagli.PutExtra("finisce", eventi[position].Fine);
            dettagli.PutExtra("descrizione", eventi[position].Descrizione);
            Application.Context.StartActivity(dettagli);
          };
        }

        return view;
    }

注意：我无法重现您上面所说的第一个问题。

Answer 2

您删除单个 for 循环中的所有项目..发送位置以删除事件

img_remove.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(eventsToRemove.size() > 0)
              events.Remove(eventsToRemove[position])
        }
    });