c# - BindingList<T> INotifyPropertyChanged 意外行为

假设，我有对象:

public interface ITest
{
    string Data { get; set; }
}
public class Test1 : ITest, INotifyPropertyChanged
{
    private string _data;
    public string Data
    {
        get { return _data; }
        set
        {
            if (_data == value) return;
            _data = value;
            OnPropertyChanged("Data");
        }
    }
    protected void OnPropertyChanged(string propertyName)
    {
        var h = PropertyChanged;
        if (null != h) h(this, new PropertyChangedEventArgs(propertyName));
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

及其持有人:

    private BindingList<ITest> _listTest1;
    public BindingList<ITest> ListTest1 { get { return _listTest1 ?? (_listTest1 = new BindingList<ITest>() { RaiseListChangedEvents = true }); }
    }

另外，我订阅了 ListChangedEvent

    public MainWindow()
    {
        InitializeComponent();
        ListTest1.ListChanged += new ListChangedEventHandler(ListTest1_ListChanged);
    }
    void ListTest1_ListChanged(object sender, ListChangedEventArgs e)
    {
        MessageBox.Show("ListChanged1: " + e.ListChangedType);
    }

和 2 个测试处理程序:
用于添加对象

    private void AddITestHandler(object sender, RoutedEventArgs e)
    {
        ListTest1.Add(new Test1 { Data = Guid.NewGuid().ToString() });
    }

和改变

    private void ChangeITestHandler(object sender, RoutedEventArgs e)
    {
        if (ListTest1.Count == 0) return;
        ListTest1[0].Data = Guid.NewGuid().ToString();
        //if (ListTest1[0] is INotifyPropertyChanged)
        //    MessageBox.Show("really pch");
    }

ItemAdded 发生，但 ItemChanged 不发生。在查看属性“数据”中，我发现我的事件 PropertyChanged 没有订阅者:

    protected void OnPropertyChanged(string propertyName)
    {
        var h = PropertyChanged; // h is null! why??
        if (null != h) h(this, new PropertyChangedEventArgs(propertyName));
    }

    public event PropertyChangedEventHandler PropertyChanged;

深入挖掘，我使用了反射器并发现了 BindingList:

    protected override void InsertItem(int index, T item)
    {
        this.EndNew(this.addNewPos);
        base.InsertItem(index, item);
        if (this.raiseItemChangedEvents)
        {
            this.HookPropertyChanged(item);
        }
        this.FireListChanged(ListChangedType.ItemAdded, index);
    }
private void HookPropertyChanged(T item)
    {
        INotifyPropertyChanged changed = item as INotifyPropertyChanged;
        if (changed != null) // Its seems like null reference! really??
        {
            if (this.propertyChangedEventHandler == null)
            {
                this.propertyChangedEventHandler = new PropertyChangedEventHandler(this.Child_PropertyChanged);
            }
            changed.PropertyChanged += this.propertyChangedEventHandler;
        }
    }

我哪里错了？或者这是已知的错误，我需要找到一些解决方法？
谢谢!

最佳答案

BindingList<T> 不检查每个特定项目是否实现 INotifyPropertyChanged 。相反，它会检查一次通用类型参数。因此，如果您的 BindingList<T> 声明如下:

private BindingList<ITest> _listTest1;

然后 ITest 应该从 INotifyPropertyChanged 继承，以获得 BindingList raise ItemChanged 事件。

关于c# - BindingList<T> INotifyPropertyChanged 意外行为，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/17039296/