observablecollection 声明的 observablecollection答案

【问题标题】：observablecollection of observablecollection declarationobservablecollection 声明的 observablecollection
【发布时间】：2016-07-11 23:55:17
【问题描述】：

不知何故，这在运行时不起作用（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？谢谢你

【问题讨论】：

标签： c# wpf observablecollection dependency-properties

【解决方案1】：

您的类型被定义为

ObservableCollection<ObservableCollection<string>>

但您将默认设置为：

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

这是一个可观察集合的数组。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>()}))

【讨论】：

【解决方案2】：

当您将字符串 ObservableCollection<string>[] 的 ObservableCollection 数组分配为 ObservableCollection<ObservableCollection<string>> 的默认值时，它不应该运行。如果你这样写代码：

        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，上面写着：

无法将类型“System.Collections.ObjectModel.ObservableCollection[]”隐式转换为“System.Collections.ObjectModel.ObservableCollection>”

相反，您可以：

        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>()};

【讨论】：