General function for opening ChildWinforms using reflection? - vb.net

Question

I'm not sure how to put this so the title may seem a little strange. I have a VB.NET MDI Winform application. In this app when I click a menuitem a child window is opened. To handle what child window must be opened I have case statement in my ToolStripMenuItem_Click event. The problem is that in every case-item the code is nearly the same. So I was wondering if it would be possible to have a general function so the code becomes more readable.
Example:
Case "mnuPrint"
Dim ChildWindowFound As Boolean = False
If Not (MdiChildren.Length.Equals(0)) Then
For Each ChildWindow As Form In MdiChildren
If ChildWindow.Name.Equals("Form1") Then
ChildWindow.Activate()
ChildWindowFound = True
End If
Next
End If
If Not ChildWindowFound Then
Dim childForm As New Form1()
childForm.Name = "Form1"
childForm.MdiParent = Me
childForm.Show()
End If
Case "mnuSearch"
Dim ChildWindowFound As Boolean = False
If Not (MdiChildren.Length.Equals(0)) Then
For Each ChildWindow As Form In MdiChildren
If ChildWindow.Name.Equals("Form2") Then
ChildWindow.Activate()
ChildWindowFound = True
End If
Next
End If
If Not ChildWindowFound Then
Dim childForm As New Form2()
childForm.Name = "Form2"
childForm.MdiParent = Me
childForm.Show()
End If
As you can see the code is nearly the same but with different forms, here Form1 and Form2 which are different, but it can be many different forms of course. The function I'm talking about would look something like:
Public Sub OpenNewForm(ByVal frm As Form, ByVal parent As Form, ByVal singleInstance As Boolean)
Dim ChildWindowFound As Boolean = False
If Not (parent.MdiChildren.Length.Equals(0)) Then
For Each ChildWindow As Form In parent.MdiChildren
If ChildWindow.Name.Equals(frm.Name) Then
ChildWindow.Activate()
ChildWindowFound = True
End If
Next
End If
If Not ChildWindowFound Then
Dim childForm As New Form
childForm.Name = frm.Name
childForm.MdiParent = Me
childForm.Show()
End If
End Sub
This doesn't work because I pass the parameters (first two) as Form-type, where it should be Form1 and ParentForm for example, not Form. I think it is possible, just don't know where to start. May be using reflection or something?
UPDATE:
Based on the answers given I came up with this code which is working fine:
'Code contributed by Rod Paddock (Dash Point Software)
'www.dashpoint.com
'Dim oForm As Form = ObjectFactory.CreateAnObject("MyApplication.frmTwo")
'oForm.Show()
Public Shared Function CreateAnObject(ByVal ObjectName As String) As Object
Dim Assem = [Assembly].GetExecutingAssembly()
Dim myType As Type = Assem.GetType(ObjectName.Trim)
Dim o As Object = Nothing
Try
o = Activator.CreateInstance(myType)
Catch oEx As TargetInvocationException
MessageBox.Show(oEx.ToString)
End Try
Return o
End Function
Public Shared Sub ActivateChildWindow(ByVal frmName As String, ByRef ParentMDIWindow As Form)
Dim ChildWindowFound As Boolean = False
With ParentMDIWindow
If Not (.MdiChildren.Length.Equals(0)) Then
For Each ChildWindow As Form In .MdiChildren
If ChildWindow.Name.Equals(frmName) Then
ChildWindow.Activate()
ChildWindowFound = True
End If
Next
End If
End With
If Not ChildWindowFound Then
Dim childForm As Form = CreateAnObject(frmName)
childForm.Name = frmName
childForm.MdiParent = ParentMDIWindow
childForm.Show()
End If

Answer 1

Maybe something like this can help you:
Dim myForm As Form = Nothing
Dim FormName As String = String.Empty
Dim formType As Type
Select Case Options
Case "mnuPrint"
FormName = "Form1"
myForm = getWindowByName(FormName)
Case "mnuSearch"
FormName = "Form2"
myForm = getWindowByName(FormName)
End Select
If myForm Is Nothing Then
formType = Type.GetType("WindowsApplication2." + FormName) 'WindowsApplication2 is my project's name
myForm = Activator.CreateInstance(formType)
myForm.Name = FormName
myForm.MdiParent = Me
myForm.Show()
Else
myForm.Activate()
End If
And the function:
Function getWindowByName(ByVal FormName As String) As Form
Dim frm As Form = Nothing
If Not (MdiChildren.Length.Equals(0)) Then
For Each ChildWindow As Form In MdiChildren
If ChildWindow.Name.Equals(FormName) Then
frm = ChildWindow
End If
Next
End If
Return frm
End Function

Answer 2

See if this will get you started. Create a project with three forms, form1 with two buttons on. Then, add this code to Form1:
Public Class Form1
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click, Button2.Click
Dim t As Type
Select Case sender.name
Case "Button1"
t = GetType(Form2)
Case "Button2"
t = GetType(Form3)
End Select
Dim f = System.Activator.CreateInstance(t)
f.show()
End Sub
End Class