dynamically loading forms

[bjswift]

I do not understand how to dynamically load a form. I have a list of choices the user can select, (from a treeview) and when the user clicks a node I want a form to load on the screen. How can I load a form dynamically?

I know how to:
dim frm as frmName
frm = new frmName
frm.show()

However, what if the frmName is not known until the user clicks one of the nodes in the treeview?

I want to:
dim frm as form
frm = new form(formNameFromTreeview)
frm.show() 'showing one of the forms clicked on.

Any help?

[HanneSThEGreaT]

Hmm, not that easy nor that difficult. The main drawback you are facing is that there is no Forms Collection in .NET, so, that means you'd have to make your own.

Follow these steps.
Add a module, to your project, by selecting Project, Add Module...
Add this to your module :

Module FormsCollection
    Public Forms As New FormsCollectionClass() 'New Collection object
    Public frm1 As New Form1 'form1
    Public frm2 As New Form2 'form2
    Public frm3 As New Form3 'form3

End Module
Class FormsCollectionClass : Implements IEnumerable
    Private c As New Collection() 'new collection
    Sub Add(ByVal f As Form) 'add form to collection
        c.Add(f)
    End Sub
    Sub Remove(ByVal f As Form) 'remove form from collection
        Dim itemCount As Integer
        For itemCount = 1 To c.Count
            If f Is c.Item(itemCount) Then
                c.Remove(itemCount)
                Exit For
            End If
        Next
    End Sub
    ReadOnly Property Item(ByVal index) As Form 'get item
        Get
            Return c.Item(index)
        End Get
    End Property
    Overridable Function GetEnumerator() As _
    IEnumerator Implements IEnumerable.GetEnumerator
        Return c.GetEnumerator 'enumerate
    End Function
End Class

Then, follow these steps to add 2 more forms to your project:
Project, Add Form...
Now, we should have three forms ( just note here, in the module I only declared 3 form objects, because I'm dealing with 3 forms - demonstration purposes now only )

On Form 1, add a Treeview, and 2 buttons - keep all the default names.
Then, add the following code to Form 1 :

Public Class Form1
    Private GetTreeText As String 'get selected from treeview
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Forms.Add(frm1) 'add form1 to collection
        Forms.Add(frm2) 'add form2 to collection
        Forms.Add(frm3) 'add form3 to collection

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim frm As Form 'loop through our forms collection, and add each form name to the treeview
        For Each frm In Forms
            TreeView1.Nodes.Add(frm.Name)
        Next
    End Sub

    Private Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
        Select Case GetTreeText 'determine selected treenode text
            Case "Form1"
                frm1.Show()
            Case "Form2"
                frm2.Show()
            Case "Form3"
                frm3.Show()
        End Select
    End Sub

    Private Sub TreeView1_AfterSelect(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect
        GetTreeText = TreeView1.SelectedNode.Text 'store selected item
    End Sub
End Class

Once run, I click button 1, then it loads all the form names into the Treeview, when I have selected a Form name from the Treeview, and clicked on Button2, it will show the particular form that was selected.

I'm attaching a sample with

I hope it helps!

[bjswift]

Thanks for the tip and the example. After posting my question, and going back to my search for a solution, I found this:

Dim objNewForm As Object = Activator.CreateInstance(Type.GetType("MyApplication." & formName))
Dim frm As Form = DirectCast(objNewForm, Form)

From there, I can open the form into a panel. It seems to work, and with less code, unless there are other reasons to keep a Forms collection?

Thanks again for your tip!