vb.net 代码以关闭另一个窗体(如果它已打开)

Question

这很简陋，但我想不通。

如果 form1 仍然打开，我想在 form2 关闭时以编程方式关闭 form1。Form2 由 form1 上的命令按钮打开。

窗体 1 上打开窗体 2 的代码是：

Dim frm As New form2
frm.Show()

当 Form2 关闭以关闭任何打开的 Form1 副本时，最好的方法是什么？

Answer 1

如果你想独立处理你的两个表单，你需要从第三个表单或类来监视它们。所以我的建议是在第三个类中创建它们，并将第二个表单的引用传递给第一个表单，以便它可以打开它。这边：

Public Class MyHelper
    Public Sub CreateForms()
        Dim form2 as New Form2()
        AddHandler form2.Closed, AddressOf Form2_OnClosed
        ‘ Create as many copies as you need
        Dim form1 as New Form1(form2)
        form1.Show()
    End Sub
    Protected Sub Form2_OnClosed(sender as object, e as EventArgs) 
        ‘ Same code for each form1 that has been created and opened.
        If (form1.IsOpen) Then form1.Close()
    End Sub
End Class

Public Class Form1
    Private _form2 as Form2
    Public Property IsOpen as Boolean = false
    Public Sub New(form2 as Form2)
        _form2 = form2
    End Sub
    Protected Sub MyButton_Click(sender as object, e as EventArgs) handles MyButton.Click
        ‘ You open your form here or wherever you want (even on the constructor)
        _form2.Show()
    End Sub
    Protected Sub Me_OnClosed(sender as object, e as EventArgs) handles Me.Closed
        Me.IsOpen = false
    End Sub
    Protected Sub Me_OnShown(sender as object, e as EventArgs) handles Me.Shown
        Me.IsOpen = true
    End Sub
End Class

Answer 2

添加此引用以使其正常工作。

Imports System.Linq
If Application.OpenForms().OfType(Of Form1).Any Then
   MsgBox("Form1 is open")
End If

Answer 3

假设您有 3 个表单，并希望在单击按钮时关闭其他两个表单

Private Sub EMPLEADOToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles EMPLEADOToolStripMenuItem.Click
    If Application.OpenForms().OfType(Of BUSCAR_INDEX).Any Then
        BUSCAR_INDEX.Close()
    ElseIf Application.OpenForms().OfType(Of MIEMBROS_INDEX).Any Then
        MIEMBROS_INDEX.Close()
    End If
    EMP_INDEX.Show()
    EMP_INDEX.EmpIDTextBox.Text = EmpIDTextBox.Text
End Sub