vb.net code to close another form if it is open - vb.net

Question

This is pretty rudimentary, but I can't figure it out.
I want to programmatically close form1 when form2 closes, if form1 is still open. Form2 was opened by a command button on form1.
The code on Form1 that opens Form2 is:
Dim frm As New form2
frm.Show()
What's the best way when Form2 closes to close any open copies of Form1 that are open, also?

Answer 1

If you want to handle your two forms independently, you need to watch over them from a third form or class. So my suggestion would be to create both of them in this third class, and pass a reference of the second form to the first form so it can then open it. This way:
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

Add this reference to make it work.
Imports System.Linq
If Application.OpenForms().OfType(Of Form1).Any Then
MsgBox("Form1 is open")
End If

Answer 3

Supposing you have 3 forms and want to close the other two on button click
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