Interaction between forms

[esposito]

Hello, I am struggling with a problem dealing with the interaction between forms in VB.NET.

 

Typically, when I load a new form using the ShowDialog method, I am unable to export any value from the form on top to the one underneath.

 

To clarify what I mean, suppose I load Form2 in the ShowDialog mode without hiding Form1, which remains visible underneath.

 

Form2 contains a listbox from which the user is allowed to select an item which will then appear in a textbox in the underlying Form1.

 

After the selection of the item, Form2 is unloaded automatically and the user finds himself again in Form1, which now contains the imported value in a specific textbox.

 

In VB6 this operation was extremely easy. All you had to do was insert the following code in the Double_Click event of the listbox contained in Form2:

 

Form1.Text1.Text = Form2.List1.Text

Unload Me

 

I'm afraid things have gotten a little more complicated in VB.NET, since everytime you make a reference to another form or to its objects, you have to create a new instance of that form.

 

In my case, Form1 is already open and so I think it doesn't make any sense to create a new istance of it, since in that way I would show the same form twice on the screen.

 

Does anybody know whether there is a solution to my problem?

 

Thanks in advance.

[mutant]

When showing you other form as a dialog simply pass in the value to the Owner argument which will then keep a reference to your original form from the dialog.

Dim f2 As New Form2
f1.ShowDialog(Me) 'pass in the reference to your current form

Then , from your dialog form access the owner like this:

'if you want to use objects that belong to your form class not the Form class
'then you have to cast the owner object to the wanted type
DirectCast(Me.Owner, Form1).TextBox1.Text = "some text"

[esposito]

Thank you very much for your help.

 

I have changed the code you gave me a little bit to get rid of the DirectCast statement, so the code I used in my project runs as follows:

 

'Launches Form2:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
   Dim f As New Form2
   f.Owner = Me
   f.ShowDialog()
End Sub

'In Form2, to make a reference to Form1:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
   Dim f As Form1
   f = Me.Owner
   f.Textbox1.Text = ListBox1.Text
End Sub

 

Thanks again.

 

When showing you other form as a dialog simply pass in the value to the Owner argument which will then keep a reference to your original form from the dialog.

Dim f2 As New Form2
f1.ShowDialog(Me) 'pass in the reference to your current form

Then , from your dialog form access the owner like this:

'if you want to use objects that belong to your form class not the Form class
'then you have to cast the owner object to the wanted type
DirectCast(Me.Owner, Form1).TextBox1.Text = "some text"