如何在backgroundworker中更改textbox.text？

Question

我只是想在後臺工作時更改文本框文本。 我所擁有的是：

Private Sub ... 

Dim powershellWorker As New BackgroundWorker 
     AddHandler powershellWorker.DoWork, AddressOf BackgroundWorker1_DoWork 

     powershellWorker.RunWorkerAsync() 

End Sub 

Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork 

If stuff <> "lol" Then 
      test.Text = stuff 

End Sub 

它給我的錯誤：「無效的線程-border操作」（谷歌翻譯）

Answer 1

不能從除線程的線程上改變大多數控件屬性哪個控件是創建的。

檢查是否需要調用，即當前的代碼在除其中控制（文本框試驗）已創建的線程以外的線程中執行。如果test.InvokeRequired爲真，那麼您應該調用該調用。

Private Sub ... 
    Dim powershellWorker As New BackgroundWorker 
    AddHandler powershellWorker.DoWork, AddressOf BackgroundWorker1_DoWork 

    powershellWorker.RunWorkerAsync() 

End Sub 

Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork 

    If stuff <> "lol" Then 
     If test.InvokeRequired Then 
      test.Invoke(Sub() test.Text = stuff) 
     Else 
      test.Text = stuff 
     End If 
    End If 
End Sub 

您可以自動使用這個擴展方法的調用所需的模式：

<Extension()> 
Public Sub InvokeIfRequired(ByVal control As Control, action As MethodInvoker) 
    If control.InvokeRequired Then 
     control.Invoke(action) 
    Else 
     action() 
    End If 
End Sub 

那麼你的代碼可以簡化爲：

Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork 

    If stuff <> "lol" Then 
     test.InvokeIfRequired(Sub() test.Text = stuff) 
    End If 
End Sub