窗体内的窗体上的文本框不更新

Question

我想了解更多关于VB.NET和多个窗体，所以我可以让我的代码更好。

我有一个SQL数据库表，它包含所有14个进程的实时数据，监视程序更新显示所有进程进度的窗体。多年前在MS Access中，我只是简单地使用滚动子窗体来显示表格的内容。然而，我第一次尝试在VB.NET中是有“很多”文本框，基本上14行文本框，我的代码有14个非常相似的部分更新所有的文本框。必须有一个更好的办法:(

例如：

txtProcessID1.Text TxtStatus1.Text ProgressBar1 ......

txtProcessID2.Text TxtStatus2.Text ProgressBar2 ......

txtProcessID3.Text TxtStatus3.Text ProgressBar3 ......

所以，我想拿出我在那里创建子窗体，看起来像一个控制器行代码，然后创建的14个实例在我的mainform上的这个子表格。

我的测试代码似乎工作，但子窗体上的文本框没有更新屏幕上的内容！即使当我回拨.text的内容时，这也是我所期望的。

为什么此示例代码不起作用，而我的解决方案是完成此操作的最佳方式？

Public Class MainForm 
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
     SubForm.SetText = Me.TextBox1.Text ' Try to change contents of a TextBox on the SubForm 
     Me.TextBox2.Text = SubForm.SetText ' Data comes back as expected, but the subform textbox remains unchanged. 
    End Sub 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load 
     Dim objSubForm As New SubForm() 
     objSubForm.TopLevel = False 
     Me.Panel1.Controls.Add(objSubForm) 
     objSubForm.Show() 
    End Sub 
End Class 

Public Class SubForm 
    Public Property SetText() As String 
     Get 
      SetText = TextBox1.Text 
     End Get 
     Set(ByVal Value As String) 
      Me.TextBox1.Text = Value     ' Control is not updated of the SubForm. 
      Debug.Print("Value = " & Value)   ' The Value is Passed Correctly. 
      Debug.Print("Text = " & TextBox1.Text) ' And the property of the control has been updated. 
     End Set 
    End Property 
End Class 

非常感谢

千电子伏

Answer 1

在你点击链接你引用的类名SubForm，这在VB.NET被称为一种形式的default automatic instance，但这是不一样的您在中显示的实例。在此创建一个名为objSubForm的不同实例，这是您显示的实例。

要解决，你需要保持objSubForm作为一个全球性的实例，是指这个全球性当你点击

Public Class MainForm 
    Dim objSubForm As SubForm 

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
     objSubForm.SetText = Me.TextBox1.Text ' Try to change contents of a TextBox on the SubForm 
     Me.TextBox2.Text = objSubForm.SetText ' Data comes back as expected, but the subform textbox remains unchanged. 
    End Sub 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load 
     objSubForm = New SubForm() 
     objSubForm.TopLevel = False 
     Me.Panel1.Controls.Add(objSubForm) 
     objSubForm.Show() 
    End Sub 
End Class 

请记住，这改变后，你有责任有效地关闭和处置的全局实例。

Private Sub Form1_FormClosed(sender as Object, e as FormClosedEventArgs) _ 
    Handles Form1.FormClosed 
    if objSubForm IsNot Nothing 
     objSubForm.Close 
    End If 
    objSubForm = Nothing 
End Sub 

Answer 2

谢谢史蒂夫，我根据您的修复在半小时内应用了新代码。

下面是我的代码的一个基本示例，它给了我可以更新的14个子表单。

我已经不再在子表单中创建属性，而是直接更新TextBox控件。

该解决方案给了我“更多”更少的代码，现在我可以添加另一个细节到一个子窗体并显示所有进程。

再次感谢！ Kev

Public Class MainForm 
Dim objSubForm(14) As SubForm 
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
    'Update the 14 forms 
    For n = 0 To 13 
     objSubForm(n).TextBox1.Text = Me.TextBox1.Text & " " & n 
    Next 
End Sub 
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load 
    ' create 14 subforms 
    For n = 0 To 13 
     objSubForm(n) = New SubForm() 
     objSubForm(n).TopLevel = False 
     Me.Panel1.Controls.Add(objSubForm(n)) 
     objSubForm(n).Location = New Point(0, 20 * n) 
     objSubForm(n).Show() 
    Next 
End Sub 
Private Sub MainForm_FormClosed(sender As Object, e As FormClosedEventArgs) Handles MyBase.FormClosed 
    ' CLear up 
    If objSubForm IsNot Nothing Then 
     For n = 0 To 13 
      objSubForm(n).Close() 
     Next 
    End If 
    For n = 0 To 13 
     objSubForm(n) = Nothing 
    Next 
End Sub 
End Class