loading forms

[theyikes]

hi guys. i have a quick question. I have a form with a command button that when i click i want to load a new form. it was easy in vb6 but i can't figure it out in vb.net

I'd love some help with this one guys.

[wes4dbt]

Just create it and then show it,

        Dim frm As New Form2
        frm.show

[dday9]

wes4dbt is correct, but you should be aware that the Form class implements IDisposable and should be disposed after you access it. Here is documentation on the subject: https://learn.microsoft.com/en-us/do...em-idisposable

If you wanted to display it as a modal then wrap the form creation in a using statement (documentation) and call the ShowDialog method (documentation):

Using frm = New Form2()
    frm.ShowDialog()
End Using

If you wanted to display it without being a modal, then you can dispose of it manually after the form closes by calling the Dispose method (documentation). You can do this in the Form's FormClosed event (documentation):

Dim frm = New Form2()

AddHandler frm.FormClosed, Sub(sender, e)
                               DirectCast(sender, Form).Dispose()
                           End Sub

frm.Show()

[theyikes]

Using frm = New Form2()
frm.ShowDialog()
End Using

just keeps bringing up the original form.

Let me explain, i have a form with a dropdown.box with form2 as an item
i need to Load form2 when a certain item is selected.

[theyikes]

i figured it out. i was loading the wrong form. thank you so much for your help!

[dday9]

I don't understand. If Form1 holds the dropdown, when the item is selected it should create a new instance of Form2 and show it.

Public Class Form1

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim selectedItem = ComboBox1.Text
        If (selectedItem.Equals("Form2", StringComparison.OrdinalIgnoreCase)) Then
            Using frm = New Form2()
                frm.ShowDialog()
            End Using
        End If
    End Sub

End Class

Attachment 190942
Attachment 190943

[Shaggy Hiker]

Then that code would be located in the SelectedIndexChanged event for the dropdown. I'm not sure what you meant by it just bringing up the original form. The code shown will create an instance of Form2 and display it. How is that the original form? I expect that there is a miscommunication here.

[dday9]

Cross posted, glad you got it resolved.

[jmcilhinney]

If you wanted to display it without being a modal, then you can dispose of it manually after the form closes by calling the Dispose method (documentation). You can do this in the Form's FormClosed event (documentation):

Dim frm = New Form2()

AddHandler frm.FormClosed, Sub(sender, e)
                               DirectCast(sender, Form).Dispose()
                           End Sub

frm.Show()

That is unnecessary. When a form is displayed by calling ShowDialog, closing it does not dispose it, so you actually do have to dispose it explicitly or via a using block. When you display a form by calling Show though, closing it actually does dispose it. It may well have been done that way specifically because having to write code to dispose forms that might even outlive their caller would be cumbersome. Less so now with the advent of lambda expressions but back in the .NET Framework 1.0 days, definitely so.

[dday9]

... When you display a form by calling Show though, closing it actually does dispose it ...

I was not aware of that. It doesn't look like that is documented anywhere in the Form's Show method (here), do you know where I can find some more information on that?

[techgnome]

It's actually (kind of) noted on ShowDialog

Because a form displayed as a dialog box is hidden instead of closed, you must call the Dispose method of the form when the form is no longer needed by your application.

Looks like there's more info about it in the Close method.

When a form is closed, all resources created within the object are closed and the form is disposed

-tg

[dbasnett]

It's actually (kind of) noted on ShowDialog


Looks like there's more info about it in the Close method.


-tg

I found this in the Reference Source. Didn't seem to matter if it was Show or ShowDialog.

// MSDN: When a form is closed, all resources created within the object are closed and the form is disposed.
// For MDI child: MdiChildren collection gets updated (VSWhidbey# 368642 & 93550)
Dispose();

[dday9]

I don't want to derail this member's thread, so I'm going to open a new one.