calling a function from another form?!!!!!

aaah, I'm confused!
How can I access a function of another form?

I have a form with a listView control on it. A form called frmAdd is called to add items to the listview control. When frmAdd is closing, I want to add the new items to my listview control. But I dont know how to access the listview control from "frmAdd". I added a function to my main form, but I cant access the function
how can I do this? is there a better way to do this anyways?:confused:

The best way to do this imho is to send a reference to the listview to your frmAdd form. Do this by changing the Public Sub New part of the frmAdd form:-

Public Sub New(ByRef lv As ListView)

This sub is the first procedure in the Windows Form Designer Generated code.

Now from your form with the list view you do the following in the procedure to open the frmAdd form:-

dim frm as new frmAdd
frm.Show(ListView1)

This assumes your listview is called ListView1 so you would change that to the correct name.
Then when the user clicks the o.k. button on the frmAdd form you just use the passed reference:-

lv.Items.Add "New Item"
....
..
.
etc.

Should work but I haven't tried it - thats up to you :)

I agree, I have been passing references as arguments to the constructor of the class for a while now. Works great. Plus, if you use the same form for different things, you can overload the constructor and allow yourself to pass it what you want depending on what you want the form/class to do.

Wow! never thought of editing the default constructor!!! tnx guys :)

Edit:
Doesnt work :(

VB Code:

Private newItems() As DB.Item
 
Public Sub New(ByRef newItems() As DB.Item)
    ' ...
    Me.newItems = newItems
End Sub

when the form is closed, the newItems array that was sent as ByRef isnt changed. the newItems() is changed before closing this form, but when it is closed it will be set to Nothing:confused:
I'm passing it as ByRef!!! why doesnt it work?

NOTE: DB is a class and DB.Item is a Structure inside it

you are using the same variable name as a decalred private and a parameter. 20 bucks thats the problem.

Quote:

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Originally posted by Cander
you are using the same variable name as a decalred private and a parameter. 20 bucks thats the problem.

---

give me 20 bucks :) that's not a problem at all becuase I'm useing the ME keyword to access the private variable thingie. Just to make sure, I changed the variable name, but that didnt change anything.

You could try setting the objects through a public property instead of a constructor, but that shouldn't make a difference.

It also shouldn't make a difference if you pass it ByVal or ByRef.

Post more code. I don't think the problem is with anything you have posted so far.

OH WELL!!! Maybe I'm still confusing C++ and VB together :D :D :D

When the form starts, the object IS equal to nothing. Let's change the example this way:

VB Code:

Private newItems() As DB.Item
 
Public Sub New(ByRef SaveValues() As DB.Item)
    ' I wish this could work like a reference
    saveValues = newItems 
End Sub
 
Private doStuff()
     ' Suppose that newItems() is chaning to another array
     newItems = .......
End Sub

I am changing newItems(), so it wont be equal to NOTHING. What I want is that whenever newItems changes, the saveValues array would change to the same value as newItems. And when the form is closing, the saveValues array would be keep alive (because it's declared on the main form)Exactly like setting a reference to a variable in C++.
kinda confusing :D

Ok, if I understand you correctly, I think I have your answer. Follow these steps.

Create two forms: form1 and form2

On form1, add a button and a label with default names. In the buttons click event, add this code:

Code:

---

        Dim frmTemp As Form2
        frmTemp = New Form2(Me)
        frmTemp.ShowDialog()

---

Also add a user created sub to that form1 class like this:

Code:

---

    Public Sub MySub()
        Label1.BackColor = System.Drawing.Color.AliceBlue
    End Sub

---

Now, on form2, add just one button, keeping the default name.
Here is where things get a little tricky, so follow closely...
First, edit the constructor to take a object variable into it and assign it to a variable we will add in next:

Code:

---

    Public Sub New(ByVal sender As System.Object)
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

        original = sender
    End Sub

---

Now, add a private "CLASS" variable to the form2 class like so (I am showing you two statements, the first is put there by VS, the second is mine. I just wanted to show you where I put it)

Code:

---

    Private components As System.ComponentModel.IContainer
    'This one is the one I added:
    Private original As System.Object

---

Now, in the buttons click event, put this code:

Code:

---

        ' This will call the MySub on form 1, which created form2.
        Dim frmTemp As Form1
        frmTemp = DirectCast(original, Form1)
        frmTemp.MySub()

---

Now, when you start and run the program, form one will show up. You push the button to bring up form2. When you push form2's button, it will call a public sub from form1. If you watch, you will see the labels color change to prove it works.

And, just in case I wasn't clear on anything, here is all the code for both forms, starting with form1.

Code:

---

'Form1's code:
Public Class Form1
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

    End Sub

    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer. 
    'Do not modify it using the code editor.
    Friend WithEvents Button1 As System.Windows.Forms.Button
    Friend WithEvents Label1 As System.Windows.Forms.Label
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Button1 = New System.Windows.Forms.Button()
        Me.Label1 = New System.Windows.Forms.Label()
        Me.SuspendLayout()
        '
        'Button1
        '
        Me.Button1.Location = New System.Drawing.Point(72, 128)
        Me.Button1.Name = "Button1"
        Me.Button1.TabIndex = 0
        Me.Button1.Text = "Button1"
        '
        'Label1
        '
        Me.Label1.Location = New System.Drawing.Point(32, 32)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(160, 23)
        Me.Label1.TabIndex = 1
        Me.Label1.Text = "Label1"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(292, 266)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.Label1, Me.Button1})
        Me.Name = "Form1"
        Me.Text = "Form1"
        Me.ResumeLayout(False)

    End Sub

#End Region

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

    Public Sub MySub()
        Label1.BackColor = System.Drawing.Color.AliceBlue
    End Sub
End Class

---

Code:

---

'Form2's code:
Public Class Form2
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "


    Public Sub New(ByVal sender As System.Object)
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

        original = sender
    End Sub

    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer
    Private original As System.Object

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer. 
    'Do not modify it using the code editor.
    Friend WithEvents Button1 As System.Windows.Forms.Button
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Button1 = New System.Windows.Forms.Button()
        Me.SuspendLayout()
        '
        'Button1
        '
        Me.Button1.Location = New System.Drawing.Point(88, 104)
        Me.Button1.Name = "Button1"
        Me.Button1.TabIndex = 0
        Me.Button1.Text = "Button1"
        '
        'Form2
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(292, 266)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.Button1})
        Me.Name = "Form2"
        Me.Text = "Form2"
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        ' This will call the MySub on form 1, which created form2.
        Dim frmTemp As Form1
        frmTemp = DirectCast(original, Form1)
        frmTemp.MySub()
    End Sub
End Class

---

tried your fist post, workz perfect!!! :) :) tnx :) :) :) :) :)


EDITED:
I'm just wondering why do you send the form as system.Object? I tried the same thing and I also tried to send the form like this

VB Code:

Private Original As Form1
    Public Sub New(ByVal frmOriginal As Form1)
        MyBase.New()
 
        'This call is required by the Windows Form Designer.
        InitializeComponent()
 
        'Add any initialization after the InitializeComponent() call
 
        original = frmOriginal
    End Sub

this works too, but why would you use system.object and then cast from it? is that any better?:confused:

The reason I did the cast is only a matter of preference thing. I was needing to pass in different object types to the constructor, so I ended up using System.Object. Your way will work, as long as form1 is the only one creating that form2.

Glad it worked for you.