Question

不知何故，这不是在运行时工作（但它正在编译）：

    public static readonly DependencyProperty SelectedVideoFileNamesProperty =
    DependencyProperty.Register("SelectedVideoFileNames", typeof(ObservableCollection<ObservableCollection<string>>), typeof(CMiX_UI), 
        new PropertyMetadata(new[]{new ObservableCollection<string>(),
                                   new ObservableCollection<string>(),
                                   new ObservableCollection<string>(),
                                   new ObservableCollection<string>(),
                                   new ObservableCollection<string>(),
                                   new ObservableCollection<string>()}));
    [Bindable(true)]
    public ObservableCollection<ObservableCollection<string>> SelectedVideoFileNames
    {
        get { return (ObservableCollection<ObservableCollection<string>>)this.GetValue(SelectedVideoFileNamesProperty); }
        set { this.SetValue(SelectedVideoFileNamesProperty, value); }
    }

为什么？谢谢

Answer 1

您的类型定义为

ObservableCollection<ObservableCollection<string>>

然而，您将默认设置为：

new[]{new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>()}))

哪个是可观察集合的数组。你需要：

new ObservableCollection<ObservableCollection<String()>> {new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>()}))

Answer 2

当您将字符串ObservableCollection<string>[]的ObservableCollection数组指定为ObservableCollection<ObservableCollection<string>>的默认值时，它不应该正在运行。如果您编写如下代码：

        ObservableCollection<ObservableCollection<string>> o = new[]{new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>()};

它会给你一个设计时错误：

无法隐式转换类型＆＃39; System.Collections.ObjectModel.ObservableCollection []＆＃39;到＆＃39; System.Collections.ObjectModel.ObservableCollection＆gt;＆＃39;

相反，你可以：

        ObservableCollection<ObservableCollection<string>> o = new ObservableCollection<ObservableCollection<string>> {new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>(),
                               new ObservableCollection<string>()};

可观察收集的可观察收集声明

2 个答案: