在线程中的类中操作窗体中的控件?

Question

代码如下:

 

Public Class Form1
    Delegate Sub SetTextCallback(ByVal [text] As String)
    Private demoThread As Thread = Nothing
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Me.demoThread = New Thread( _
        New ThreadStart(AddressOf Me.ThreadProcUnsafe))

        Me.demoThread.Start()
    End Sub
    Private Sub ThreadProcUnsafe()
        Dim a As New cc
        a.SetText("This text was set safely.")
    End Sub
    Class cc
        Public Sub SetText(ByVal [text] As String)
            If Form1.TextBox1.InvokeRequired Then
                Dim d As New SetTextCallback(AddressOf SetText)
                Form1.Invoke(d, New Object() {[text]})
            Else
                Form1.TextBox1.Text = [text]
            End If
        End Sub
    End Class
End Class

 

执行以后,窗体中的文本框中的文本没有变化?

 

在运行的时候也没报错,语句执行后为什么反应呢???

 

 

Answer 1

 

Code Snippet

Delegate Sub SetTextCallback(ByVal frm As Form1, ByVal [text] As String)

 

 

Code Snippet

 

a.SetText(Me, "This text was set safely.")

 

 

Code Snippet

 

Public Sub SetText(ByVal frm As Form1, ByVal [text] As String)
        If frm.InvokeRequired Then
            Dim d As New SetTextCallback(AddressOf SetText)
            frm.Invoke(d, New Object() {frm, [text]})
        Else
            frm.TextBox1.Text = [text]
        End If
    End Sub

 

 

 

Answer 2

在同一个类中我也能实现,但在不同类中就不行,但我已经找到了原因,因为在不同的类中只能访问shared成员!