Question

我有一个长列表选择器，其中我显示按日期排序的数据。我面临的问题是列表第一次成功加载，但在返回到详细页面中包含longlistselctor的页面后，应用程序崩溃，出现以下异常： System.NullReferenceException was unhandled Message=NullReferenceException StackTrace: at Microsoft.Phone.Controls.LongListSelector.Balance() at Microsoft.Phone.Controls.LongListSelector.LongListSelector_LayoutUpdated(Object sender, EventArgs e) at System.Windows.FrameworkElement.OnLayoutUpdated(Object sender, EventArgs e) at MS.Internal.JoltHelper.RaiseEvent(IntPtr target, UInt32 eventId, IntPtr coreEventArgs, UInt32 eventArgsTypeIndex)

由于发生了什么，我甚至无法追查。该列表填充为：

currentAudioList = DiaryDBController.DBController.GetDiaryRecordsWithAudio();



        var DiaryAudioRecordsByDate = from rec in currentAudioList
                                      group rec by rec.CreationDate into r
                                      orderby r.Key
                                      select new Group<DatabaseClasses.DiaryRecord>(r.Key, r);

        try
        {
            this.AudioGroupListSelector.ItemsSource = DiaryAudioRecordsByDate;
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine(ex);
        }

var DiaryAudioRecordsByDate = from rec in currentAudioList group rec by rec.CreationDate into r orderby r.Key select new Group<DatabaseClasses.DiaryRecord>(r.Key, r); try { this.AudioGroupListSelector.ItemsSource = DiaryAudioRecordsByDate; } catch (Exception ex) { System.Diagnostics.Debug.WriteLine(ex); }

任何帮助将不胜感激。感谢。

Answer 1

我遇到了同样的问题，在Codeplex上报告here以及可能的解决方法。

看起来可以通过更改LongListSelector.Balance（）方法的第一行来解决问题：

if( !IsReady() || _flattenedItems.Count == 0 )

到

if( !IsReady() || _flattenedItems == null || _flattenedItems.Count == 0 )

加载LongListSelector时崩溃

1 个答案: