C# - 如果我使用 backgroundWorker，treeView 控件中不会显示任何内容

Question

我喜欢在 "treeView1" 控件中填充数组 "numbers"。如果我不使用 backgroundWorker 控件，一切都很好。

如果我使用 backgroundWorker，treeView1 中不会显示任何内容。看起来代码卡在了 foreach 循环中。

        //Step1
    private void button1_Click(object sender, EventArgs e)
    {          
        CheckForIllegalCrossThreadCalls = false;
        backgroundWorker1.RunWorkerAsync();
        button1.Enabled = false;
    }

    //Step2
    private void backgroundWorker1_DoWork_1(object sender, DoWorkEventArgs e)
    {
        int[] numbers = new int[5];
        numbers[0] = 1;
        numbers[1] = 2;
        numbers[2] = 3;
        numbers[3] = 4;
        numbers[4] = 5;

        foreach (int element in numbers)
        {
            treeView1.Nodes.Add(element.ToString());
        }
        button1.Enabled = true;
    }

我尝试了您在下面建议的所有方法，但仍然没有显示任何内容

        //Step1
    private void button1_Click(object sender, EventArgs e)
    {

        CheckForIllegalCrossThreadCalls = true;
        backgroundWorker1.WorkerReportsProgress = true;
        backgroundWorker1.WorkerSupportsCancellation = true;
        backgroundWorker1.RunWorkerAsync();
        button1.Enabled = false;
    }

    //Step2
    private void backgroundWorker1_DoWork_1(object sender, DoWorkEventArgs e)
    {
        this.treeView1.Nodes.Clear();

        int[] numbers = new int[5];
        numbers[0] = 1;
        numbers[1] = 2;
        numbers[2] = 3;
        numbers[3] = 4;
        numbers[4] = 5;
        treeView1.BeginUpdate();
        foreach (int element in numbers)
        {
            treeView1.Nodes.Add(element.ToString());
        }
        treeView1.EndUpdate();
        button1.Enabled = true;
        treeView1.Refresh();
    }

感谢 Banjamin 现在所有的工作:)

        //Step1
    private void button1_Click(object sender, EventArgs e)
    {

        CheckForIllegalCrossThreadCalls = false;
        backgroundWorker1.WorkerReportsProgress = true;
        backgroundWorker1.WorkerSupportsCancellation = true;
        backgroundWorker1.RunWorkerAsync();
        button1.Enabled = false;
    }

    //Step2
    private void backgroundWorker1_DoWork_1(object sender, DoWorkEventArgs e)
    {
        this.treeView1.Nodes.Clear();

        int[] numbers = new int[5];
        numbers[0] = 1;
        numbers[1] = 2;
        numbers[2] = 3;
        numbers[3] = 4;
        numbers[4] = 5;

        treeView1.Invoke((Action)delegate
        {
            foreach (int element in numbers)
            {
                treeView1.Nodes.Add(element.ToString());
            }
        });

        treeView1.EndUpdate();
        //button1.Enabled = true;
        treeView1.Refresh();
        System.Windows.Forms.MessageBox.Show("Completed");
        button1.Invoke((Action)delegate { button1.Enabled = true; });
    }

Answer 1

如果您运行在调试器中编写代码，您将看到一个异常弹出窗口，为您提供有关错误原因的更多详细信息：

Additional information: Action being performed on this control is being called from the wrong thread. Marshal to the correct thread using Control.Invoke or Control.BeginInvoke to perform this action.

您应该始终从应用程序的主线程（或 window）更新您的 UI。正确的代码是：

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    int[] numbers = new int[5];
    numbers[0] = 1;
    numbers[1] = 2;
    numbers[2] = 3;
    numbers[3] = 4;
    numbers[4] = 5;

    treeView1.Invoke((Action)delegate 
    {
       foreach (int element in numbers)
       {
           treeView1.Nodes.Add(element.ToString());
       }
   });

   button1.Invoke((Action) delegate { button1.Enabled = true; });
}

通过在 treeView1 和 button1 上使用 Invoke 方法，您可以确保使用正确的线程来更新 UI。

C# - 如果我使用 backgroundWorker，treeView 控件中不会显示任何内容

C# - If I use backgroundWorker nothing is displayed in the treeView control

c#

loops

foreach

treeview

backgroundworker