Question

的定义

public interface INotifyPropertyChanged
{
    event PropertyChangedEventHandler PropertyChanged;
}

ObservableCollection<T>实现了这个......

public class ObservableCollection<T> : Collection<T>, INotifyCollectionChanged, INotifyPropertyChanged
{
    protected virtual event PropertyChangedEventHandler PropertyChanged;
}

当我测试这个......

public class Test : INotifyPropertyChanged
{
    protected virtual event PropertyChangedEventHandler PropertyChanged;
}

我收到以下错误：

Test没有实现接口成员＆＃39; System.ComponentModel.INotifyPropertyChanged.PropertyChanged＆＃39 ;. ＆＃39; Test.PropertyChanged＆＃39;无法实现接口成员，因为它不公开。

这怎么可能？

Answer 1

接口本身是显式实现的，具有要覆盖的类的受保护事件

public class Test : INotifyPropertyChanged
{
   // explicit interface implementation
    event PropertyChangedEventHandler INotifyPropertyChanged.PropertyChanged
    {
        add
        {
            PropertyChanged += value;
        }
        remove
        {
            PropertyChanged -= value;
        }
    }

    // protected virtual (for derived classes to override)   
    protected virtual event PropertyChangedEventHandler PropertyChanged;
}

Answer 2

除了受保护的PropertyChanged event之外，ObservableCollection<T>还为INotifyPropertyChanged.PropertyChanged event提供了明确的界面实现，这在您的课程中是缺少的（并且未在{{1的代码段中显示） }}）。

您可以阅读explicit interface implementation on MSDN。

ObservableCollection <t>如何将INotifyPropertyChanged实现为受保护的？</t>

2 个答案: