Question

当我在按钮单击处理程序中调用ObservableCollection上的.Clear（）时，间歇性地收到此错误。我很困惑，因为我确实有其他TPL任务在运行，但都通过以下方式更新了ObservableCollection：

mainWindow.Dispatcher.Invoke(new Action(delegate()
{
 this.myCollection.Add(myItem);
}));

essense中的调度程序是否使我的ObservableCollection线程安全，因为所有操作在主UI线程上都是原子的？顺便说一句：我也在DispatcherTimer中更新集合成员的某些字段，但没有在timer.tick处理程序中删除或添加项目。

詹姆斯：

我创建了一个示例应用程序来隔离问题，但样本一切正常。因此，我的应用程序中的其他内容必须将collectionchanged绊倒在另一个线程上。这一切都很好，你可以。清除没有错误：

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
<StackPanel>
    <Button Name="clear" Height="23" Click="clear_Click"></Button>
    <ListBox ItemsSource="{Binding MyCollection}">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <TextBlock Text="{Binding Name}"></TextBlock>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
</StackPanel>

    public partial class MainWindow : Window
{
    private DispatcherTimer myTimer = null;

    public MainWindow()
    {
        InitializeComponent();
        this.DataContext = this;
        Loaded +=new RoutedEventHandler(MainWindow_Loaded);
    }

    private bool isLoaded = false;
    void  MainWindow_Loaded(object sender, RoutedEventArgs e)
    {
        if (isLoaded) return;
        isLoaded = true;

        var task = new Task(() => AddObjectsTask());
        task.Start();


        myTimer = new DispatcherTimer();
        myTimer.Interval = new TimeSpan(0, 0, 1);
        myTimer.Tick += new EventHandler(myTimer_Tick);
        myTimer.Start();

        _MyCollection.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler(_MyCollection_CollectionChanged);

    }

    void _MyCollection_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
    {
        if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Add)
        {
            var query = (from n in _MyCollection select n).ToList();
            if (query.Any())
            {
                foreach (SomeObject o in query)
                {
                    o.Name = (Convert.ToInt64(o.Name) + 1).ToString();
                }
            }
        }
    }

    void myTimer_Tick(object sender, EventArgs e)
    {
        this._MyCollection.Add(new SomeObject() { Name = 99.ToString() }); 
    }

    void AddObjectsTask()
    {
        int i = 0;
        while(true)
        {
        Thread.Sleep(10);
        this.Dispatcher.Invoke(new Action(delegate() 
        { 
            this._MyCollection.Add(new SomeObject() { Name = i.ToString() }); 
        })); 
            i++;
        }
    }


    private void clear_Click(object sender, RoutedEventArgs e)
    {
        _MyCollection.Clear();
    }

    private ObservableCollection<SomeObject> _MyCollection = new ObservableCollection<SomeObject>();
    public ObservableCollection<SomeObject> MyCollection
    {
        get
        {
            return _MyCollection;
        }
    }

}

public class SomeObject : INotifyPropertyChanged
{
    #region INotifyPropertyChanged
    public event PropertyChangedEventHandler PropertyChanged;
    public void NotifyPropertyChanged(String info)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }
    #endregion

    private string _Name = string.Empty;

    public string Name
    {
        get
        {
            return _Name;
        }
        set
        {
            _Name = value;
            NotifyPropertyChanged("Name");
        }
    }
}

在CollectionChanged事件TPL期间无法更改ObservableCollection

0 个答案: