【发布时间】：2021-10-25 16:23:11
【问题描述】：
我有 3 个表单，即 MainForm、Form1 和 Form2。 MainForm 在 Panel 中托管 Form1。在 MainForm 中单击 button 时，我正在使用 ShowDialog() 方法打开 Form2。现在我在Form2 中有一个treeview。 现在我想将 Form2 中选择的节点传递回 Form1 中的 combobox。如何做到这一点？我在 Form2 中尝试过 Form1.Activate()，但代码没有在 Form1 中达到 Activate 方法。
我也在使用Form1.ComboBox1.Items.Add(Me.TreeView1.SelectedNode.Text)，但是一旦 Form2 关闭，我就看不到 ComboBox 中的任何项目。我在这里错过了什么？
下面是更好理解的代码。
MainForm
public Class MainForm
private Sub OpenChildForm(childForm As Form)
panelFormContainer.Controls.Add(childForm)
childForm.Dock = DockStyle.Fill
childForm.Show()
End Sub
private sub MainForm_OnLoad(sender As Object, e as EventArgs) Handles Me.Load
'Adding child form to a Panel in Main Form
OpenChildForm(new Form1())
End Sub
'Open Form 2 on Button Click
private sub btnOpenForm3_Click(sender As Object, e as EventArgs) Handles btnOpenForm3.Click
Form2.ShowDialog()
End Sub
End Class
Form2 - Child Form Opened by button click in MainForm
Public Class Form2
'Click back button to go back to Main Form which is already having Form1 as child
Private Sub btnBack_Click(sender As Object, e As EventArgs)
Me.Close()
Form1.Activate()
End Sub
'Click a Button to Add Selected Treeview node to Combo in Form1
Private Sub btnAdd_Click(sender As Object, e As EventArgs) btnAdd.Click
Form1.ComboBox1.Items.Add(Me.TreeView1.SelectedNode.Text)
End Sub
End Class
更新：我已经更新了代码，但在 Child Form1 的 ComboBox 中仍然没有得到任何东西
MainForm
Public Class Form1
Private currentChildForm As Form = Nothing
Private ownerForm As Form = Nothing
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
OpenChildForm(New ChildForm1())
End Sub
Private Sub OpenChildForm(childForm As Form)
If currentChildForm IsNot Nothing Then
currentChildForm.Close()
End If
childForm.TopLevel = False
childForm.FormBorderStyle = FormBorderStyle.None
panelFormContainer.Controls.Clear()
panelFormContainer.Controls.Add(childForm)
childForm.Dock = DockStyle.Fill
childForm.BringToFront()
childForm.Show()
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim dialogForm As ChildForm2 = New ChildForm2()
'
Dim result = dialogForm.ShowDialog()
If result = DialogResult.OK Then
AddHandler ChildForm2.Button1.Click, AddressOf ChildForm1.objForm2_Passvalue
End If
End Sub
End Class
ChildForm1 which is hosted in MainForm
Public Class ChildForm1
Private Sub ChildForm1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
If ComboBox1.Items.Count > 0 Then
ComboBox1.SelectedIndex = 0
End If
End Sub
Private Sub ChildForm1_Activated(sender As Object, e As EventArgs) Handles Me.Activated
End Sub
Public Sub objForm2_Passvalue(sender As Object, e As EventArgs)
Me.ComboBox1.Items.Add(PageDetail.PageTitle)
End Sub
End Class
ChildForm2 -- Which is opened as Dialog
Public Class ChildForm2
Private Sub ChildForm2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
TreeView1.ExpandAll()
Button1.DialogResult = DialogResult.OK
End Sub
Public Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
PageDetail.PageTitle = TreeView1.SelectedNode.Text
Me.Close()
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Me.Close()
End Sub
End Class
PageDetail: Class used to get and set data
Public NotInheritable Class PageDetail
Private Shared pageTitleValue As String
Public Shared Property PageTitle As String
Get
Return pageTitleValue
End Get
Set(value As String)
pageTitleValue = value
End Set
End Property
End Class
【问题讨论】：
-
有很多方法可以做到这一点，最好的方法完全取决于你。由于您执行 Form2.ShowDialog()，您可以简单地更改 TreeView1 上的访问修饰符，以便在 btnOpenForm3_Click 事件中对 MainForm 可见。您可能还想阅读默认表单实例。 Form1 和 Form2，可能不是您要查找的表单的实际实例
-
什么是
PageDetail.PageTitle？ -
@user9938：它只是一个具有设置数据属性的类。也将其添加到代码中。
-
我添加了另一个解决方案，展示了在表单之间传递数据的更多方法。希望其中一个对您有用。