Question

我喜欢填充数组＆＃34;数字＆＃34;在＆＃34; treeView1＆＃34;控制。如果我不使用backgroundWorker控件，一切正常。

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

enter image description here

        //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;
    }

我尝试了下面建议的所有内容，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

如果您在调试器中运行代码，您将获得一个异常弹出窗口，为您提供有关出错的更多详细信息：

附加信息：正在从错误的线程调用正在对此控件执行的操作。使用Control.Invoke或Control.BeginInvoke对正确的线程进行Marshal来执行此操作。

您应该始终从应用程序的主（或窗口）线程更新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，确保使用正确的线程来更新UI。

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

1 个答案: