窗體內的窗體上的文本框不更新

Question

我想了解更多關於VB.NET和多個窗體，所以我可以讓我的代碼更好。

我有一個SQL數據庫表，它包含所有14個進程的實時數據，監視程序更新顯示所有進程進度的窗體。多年前在MS Access中，我只是簡單地使用滾動子窗體來顯示錶格的內容。然而，我第一次嘗試在VB.NET中是有「很多」文本框，基本上14行文本框，我的代碼有14個非常相似的部分更新所有的文本框。必須有一個更好的辦法:(

例如：

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

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

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

所以，我想拿出我在那裏創建子窗體，看起來像一個控制器行代碼，然後創建的14個實例在我的mainform上的這個子表格。

我的測試代碼似乎工作，但子窗體上的文本框沒有更新屏幕上的內容！即使當我回撥.text的內容時，這也是我所期望的。

爲什麼此示例代碼不起作用，而我的解決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 

非常感謝

千電子伏

Answer 1

在你點擊鏈接你引用的類名SubForm，這在VB.NET被稱爲一種形式的default automatic instance，但這是不一樣的您在中顯示的實例。在此創建一個名爲objSubForm的不同實例，這是您顯示的實例。

要解決，你需要保持objSubForm作爲一個全球性的實例，是指這個全球性當你點擊

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 

請記住，這改變後，你有責任有效地關閉和處置的全局實例。

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

謝謝史蒂夫，我根據您的修復在半小時內應用了新代碼。

下面是我的代碼的一個基本示例，它給了我可以更新的14個子表單。

我已經不再在子表單中創建屬性，而是直接更新TextBox控件。

該解決方案給了我「更多」更少的代碼，現在我可以添加另一個細節到一個子窗體並顯示所有進程。

再次感謝！ 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