跨线程操作无效：控件“ label1”是从创建该线程的线程之外的线程访问的

Question

可能重复：
为什么我收到此错误：“跨线程操作无效：控制lbFolders从创建该线程的线程之外的其他线程访问。”？

我是winforms的新手，在我的代码中，我正在使用for循环更新进度条，现在我需要以循环计数的形式更新Label，如下所示-

公共部分类Form1：表单{public Form1（）{InitializeComponent（）;

        Shown += new EventHandler(Form1_Shown);

        // To report progress from the background worker we need to set this property
        backgroundWorker1.WorkerReportsProgress = true;
        // This event will be raised on the worker thread when the worker starts
        backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
        // This event will be raised when we call ReportProgress
        backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    void Form1_Shown(object sender, EventArgs e)
    {
        // Start the background worker
        backgroundWorker1.RunWorkerAsync();
    }


    // On worker thread so do our thing!
    void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        // Your background task goes here
        for (int i = 0; i <= 100; i++)
        {
            label1.Text = "Trade" + i;
            // Report progress to 'UI' thread
            backgroundWorker1.ReportProgress(i);
            // Simulate long task
            System.Threading.Thread.Sleep(100);
        }
    }
    // Back on the 'UI' thread so we can update the progress bar
    void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        // The progress percentage is a property of e
        progressBar1.Value = e.ProgressPercentage;
    }

}

但是在访问label1时，它抛出错误-

跨线程操作无效：从创建该线程的线程以外的线程访问控件“ label1”。

如何更新label1的文本

Answer 1

您只能从创建该控件的线程（即 UI 线程）访问该控件。在其他线程（例如您的BackgroundWorker）中，您需要使用Control.BeginInvoke。

label1.BeginInvoke(delegate { label1.Text = "Trade" + i; });

Answer 2

在进度处理程序中而不是在工作线程中更新标签。

// On worker thread so do our thing! 
 void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) 
 { 
     // Your background task goes here 
     for (int i = 0; i <= 100; i++) 
     { 
         // Report progress to 'UI' thread 
         backgroundWorker1.ReportProgress(i); 
         // Simulate long task 
         System.Threading.Thread.Sleep(100); 
     } 
 } 
 // Back on the 'UI' thread so we can update the progress bar - and our label :)
 void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e) 
 { 
     // The progress percentage is a property of e 
     progressBar1.Value = e.ProgressPercentage; 
     label1.Text = String.Format("Trade{0}",e.ProgressPercentage);
 }