System.invalidoperationexception：'items collection在使用itemssource之前必须为空。' [英] System.invalidoperationexception: 'items collection must be empty before using itemssource.'

问题描述

当我点击按钮系统时抛出异常

When I click on the button system throws exception

System.InvalidOperationException: 'Items collection must be empty before using ItemsSource.'

我无法找到问题



我的尝试：



点击这样的按钮我想创建一个树

I am unable to find the problem

What I have tried:

I am trying to create a tree when click on a button like this

<pre>private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            var subModules = new List<ITreeNode>
        {
            new SubModule { Name = "Sub Module 1" }
        };
            var subThreads = new List<ITreeNode>
        {
            new SubThread { Name = "Sub Thread 1" }
        };
            var nodes = new List<ITreeNode>
        {
            new Thread { Name = "Thread ", ChildNodes = subThreads },
            new Module { Name = "Module ", ChildNodes = subModules }
        };
            var processes = new List<RunProcesses>
        {
            new RunProcesses{ Name = "Process1", ChildNodes = nodes }
        };
            TreeView.ItemsSource = processes;

        }

推荐答案

阅读错误信息，它非常明确：

Read the error message, it's pretty explicit:

System.InvalidOperationException: 'Items collection must be empty before using ItemsSource.'

您正在设置已包含数据的集合（Treeview）的ItemsSource属性。



检查您的XAML，或清空Items Collection。

You are setting the ItemsSource property of a collection (the Treeview) which already has data in it.

Check your XAML, or empty the Items Collection.

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