.NET：在集合上调用 .Add 时出现 ArgumentOutOfRangeException（Pivot 控件出现问题）

Question

我遇到了异常，但我不明白为什么：

    public static void AddAll<T>(this ICollection<T> dest, ICollection<T> source)
    {
        if (dest == null)
        {
            throw new ArgumentNullException("dest");
        }

        foreach (T t in source)
        {
            // Argument out of range exception
            // Message: "\r\nParameter name: index"
            dest.Add(t);
        }
    }

例外是：

$exception  {"\r\nParameter name: index"}   System.Exception {System.ArgumentOutOfRangeException}

堆栈跟踪：

   at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource)
   at System.ThrowHelper.ThrowArgumentOutOfRangeException()
   at System.Collections.Generic.List`1.get_Item(Int32 index)
   at System.Collections.Generic.List`1.System.Collections.IList.get_Item(Int32 index)
   at System.Windows.Controls.ItemCollection.GetItemImpl(Int32 index)
   at System.Windows.Controls.ItemCollection.GetItemImplSkipMethodPack(Int32 index)
   at System.Windows.PresentationFrameworkCollection`1.get_Item(Int32 index)
   at Microsoft.Phone.Controls.Primitives.PivotHeadersControl.FadeInItemIfNeeded(Int32 index, Int32 visualFirstIndex, Int32 previousVisualFirstIndex, Int32 itemCount)
   at Microsoft.Phone.Controls.Primitives.PivotHeadersControl.UpdateItemsLayout()
   at Microsoft.Phone.Controls.Primitives.PivotHeadersControl.OnItemsChanged(NotifyCollectionChangedEventArgs e)
   at System.Windows.Controls.ItemsControl.OnItemCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Windows.Controls.ItemCollection.NotifyCollectionChanged(NotifyCollectionChangedEventArgs e)
   at System.Windows.Controls.ItemCollection.UpdateItemsSourceList(IEnumerable newItemsSource)
   at System.Windows.Controls.ItemsControl.ItemsSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
   at System.Windows.DependencyObject.RaisePropertyChangeNotifications(DependencyProperty dp, Object newValue, Object oldValue)
   at System.Windows.DependencyObject.SetValueInternal(DependencyProperty dp, Object value, Boolean allowReadOnlySet, Boolean isSetByStyle, Boolean isSetByBuiltInStyle, PropertyInvalidationReason reason)
   at System.Windows.DependencyObject.SetValueInternal(DependencyProperty dp, Object value)
   at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
   at System.Windows.Controls.ItemsControl.set_ItemsSource(IEnumerable value)
   at Microsoft.Phone.Controls.Pivot.UpdateHeaders()
   at Microsoft.Phone.Controls.Pivot.OnItemsChanged(NotifyCollectionChangedEventArgs e)
   at System.Windows.Controls.ItemsControl.OnItemCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Windows.Controls.ItemCollection.NotifyCollectionChanged(NotifyCollectionChangedEventArgs e)
   at System.Windows.Controls.ItemCollection.System.Windows.Controls.ICollectionChangedListener.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Windows.Controls.WeakCollectionChangedListener.SourceCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
   at System.Collections.ObjectModel.ObservableCollection`1.InsertItem(Int32 index, SectionViewModel item)
   at System.Collections.ObjectModel.Collection`1.Add(SectionViewModel item)
   at MyApp.ExtensionMethods.AddAll[T](ICollection`1 dest, ICollection`1 source)
   at MyApp.Sections.get_SectionViewModels()
   at System.Reflection.RuntimeMethodInfo.InternalInvoke(RuntimeMethodInfo rtmi, Object obj, BindingFlags invokeAttr, Binder binder, Object parameters, CultureInfo culture, Boolean isBinderDefault, Assembly caller, Boolean verifyAccess, StackCrawlMark& stackMark)
   at System.Reflection.RuntimeMethodInfo.InternalInvoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, StackCrawlMark& stackMark)
   at System.Reflection.RuntimePropertyInfo.InternalGetValue(PropertyInfo thisProperty, Object obj, Object[] index, StackCrawlMark& stackMark)
   at System.Reflection.RuntimePropertyInfo.GetValue(Object obj, Object[] index)
   at System.Windows.CLRPropertyListener.get_Value()
   at System.Windows.PropertyAccessPathStep.get_Value()
   at System.Windows.PropertyPathListener.RaisePropertyPathStepChanged(PropertyPathStep source)
   at System.Windows.PropertyAccessPathStep.RaisePropertyPathStepChanged(PropertyListener source)
   at System.Windows.CLRPropertyListener.SourcePropertyChanged(Object sender, PropertyChangedEventArgs args)
   at System.Windows.Data.WeakPropertyChangedListener.PropertyChangedCallback(Object sender, PropertyChangedEventArgs args)
   at MyApp.Sections.onPropChanged(String name)
   at MyApp.Sections.Sections_Loaded(Object sender, RoutedEventArgs e)
   at System.Windows.CoreInvokeHandler.InvokeEventHandler(Int32 typeIndex, Delegate handlerDelegate, Object sender, Object args)
   at MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr unmanagedObjArgs, Int32 argsTypeIndex, String eventName)

dest 是一个 ObservableCollection，当前包含 t。

source 是一个列表，包含 7 个成员。

t 是source 的第一个成员。

为什么会发生这种情况？

更新：dest 是Pivot 的ItemsSource。 Pivot 正在监听 dest.CollectionChanged，我认为这是导致问题的原因。

<controls:Pivot Title="SECTIONS" x:Name="pivotControl" ItemsSource="{Binding SectionViewModels}"> <!-- ... --> <controls:Pivot />

这是枢轴控件绑定到的属性：

        private ObservableCollection<SectionViewModel> _sectionViewModels;
        public ObservableCollection<SectionViewModel> SectionViewModels
        {
            get
            {
                // don't do anything if we haven't loaded yet
                if (NavigationContext == null)
                {
                    return null;
                }

                if (_sectionViewModels == null)
                {
                    _sectionViewModels = new ObservableCollection<SectionViewModel>();
                    _sectionViewModels.AddAll(SunData.GetSections().Select(section => new SectionViewModel(section)).ToList());

                    foreach (SectionViewModel sectionViewModel in _sectionViewModels)
                    {
                        SunData.GetStories(sectionViewModel.Section, () =>
                            {
                                onPropChanged("LoadingBarVisibility");
                            });
                    }
                }

                // re-index the source so we don't get an annoying transition animation
                // http://stackoverflow.com/questions/4541020/
                int activeVID = int.Parse(NavigationContext.QueryString[Section.SectionsKey]);

                SectionViewModel selectedItem = _sectionViewModels.Where(sectionVM => sectionVM.Section.Vid == activeVID).Single();
                int selectedIndex = _sectionViewModels.IndexOf(selectedItem);

                // one way to reindex
                for (int i = 0; i < selectedIndex; i++)
                {
                    SectionViewModel sectionVM = _sectionViewModels[0];
                    _sectionViewModels.Remove(sectionVM);
                    _sectionViewModels.Add(sectionVM);
                }

                // another way to reindex
/*
                IList<SectionViewModel> reindexedSectionVMs = new List<SectionViewModel>();
                for (int i = 0; reindexedSectionVMs.Count != _sectionViewModels.Count; i++)
                {
                    reindexedSectionVMs.Add(_sectionViewModels[(selectedIndex + i) % _sectionViewModels.Count]);
                }

                _sectionViewModels.Clear();
                _sectionViewModels.AddAll(reindexedSectionVMs);
*/
                return _sectionViewModels;
            }
        }

上面代码中的关键部分是重新索引源部分。如果我将其注释掉，我不会遇到此问题，也不会遇到许多其他错误（例如 PivotItem 的内容为空，或者选择了错误的 PivotItem。）

我尝试了两种重新索引列表的方法，但它们都导致相同的错误。

我不确定我在这里做什么会导致这些问题。

Answer 1

我在我的问题中找到了解决方案：

Argument invalid exception while navigating

Answer 2

啊哈，我明白了。这不是您的 2 个集合或您上面显示的代码的问题。问题是您通过更改事件观察这些集合，并且那里的事件处理代码有问题。

希望这些信息足以帮助您发现问题。如果没有，那么如果您发布事件处理代码，我们也许可以提供进一步的帮助。