add from listbox to listbox in seperate forms

[Rob Frank]

ok so i have 3 forms. 2 of which are populated and i need to take the selected items from those listboxes and add it to the main which is empty. so this is what i have. I have no errors but it also does nothing. any help will be appreciated.

this is the form that contains the empty listbox.

Public Class MainForm
    'add menu items to print books list box

    Private Sub ToolStripMenuItem1_Click(sender As Object, e As EventArgs) Handles mnuFile.Click

    End Sub

    Private Sub frmMain_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub

    Public Sub mnuPrint_Click(sender As Object, e As EventArgs) Handles mnuPrint.Click
        'create an instance of the PrintForm
        Dim frmPrint As New PrintForm

        'display the PrintForm
        frmPrint.Show()
        'add menu items to list box
        frmPrint.lstPrint.Items.Add("I Did It Your Way (Print)")
        frmPrint.lstPrint.Items.Add("The History of Scotland(Print)")
        frmPrint.lstPrint.Items.Add("Learn Calculus in One Day(Print)")
        frmPrint.lstPrint.Items.Add("Feel the Stress(Print)")

    End Sub

    Public Sub mnuAudio_Click(sender As Object, e As EventArgs) Handles mnuAudio.Click
        'create an instance of the AudioForm
        Dim frmAudio As New AudioForm
        'display the AudioForm
        frmAudio.Show()
        'add menu items to list box
        frmAudio.lstAudio.Items.Add("Learn Calculus in One Day(Audio)")
        frmAudio.lstAudio.Items.Add("Relaxation Techniques(Audio)")
        frmAudio.lstAudio.Items.Add("The History of Scotland(Audio)")
        frmAudio.lstAudio.Items.Add("The Science of Body Language(Audio)")

    End Sub

    Private Sub mnuAbout_Click(sender As Object, e As EventArgs) Handles mnuAbout.Click
        'display a simple about box
        MessageBox.Show("Book Selector System Version 1.0")
    End Sub

    Public Sub lstCart_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstCart.SelectedIndexChanged

    End Sub
End Class

and this is one of my populated listboxes that i'm trying to remove items from there and add them to the main listbox.

Public Class PrintForm
    Private Sub lstPrint_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstPrint.SelectedIndexChanged

    End Sub

    Private Sub btnAddPrint_Click(sender As Object, e As EventArgs) Handles btnAddPrint.Click

        Dim frmMain As New MainForm
        For Each item In lstPrint.SelectedItems
            frmMain.lstCart.Items.Add(item)
        Next


    End Sub
End Class

i believe my problem is in line 8 of my second form. I have it as New MainForm. which i assume is creating a new form as it implies. i want to modify the current form that is already being displayed. I'm not sure what to put there instead of new though since i really just want to modify it.

[Rob Frank]

ok so i fixed it half way. i can have it add items like i need. no problem there. however i want it to also remove the items from that list box as they are added to the next. what i have is.

Public Class PrintForm
    Private Sub lstPrint_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstPrint.SelectedIndexChanged

    End Sub

    Private Sub btnAddPrint_Click(sender As Object, e As EventArgs) Handles btnAddPrint.Click


        For Each item In lstPrint.SelectedItems
            MainForm.lstCart.Items.Add(item)

        Next




    End Sub
End Class

if i add this i get Exception thrown: 'System.InvalidOperationException' in System.Windows.Forms.dll

Public Class PrintForm
    Private Sub lstPrint_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstPrint.SelectedIndexChanged

    End Sub

    Private Sub btnAddPrint_Click(sender As Object, e As EventArgs) Handles btnAddPrint.Click


        For Each item In lstPrint.SelectedItems
            MainForm.lstCart.Items.Add(item)
'This is what i added and get the error
            lstPrint.Items.Remove(item)

        Next




    End Sub
End Class

[Rob Frank]

well i guess i'm just posting this for anyone searching the web for the answer like me lol. took me awhile to find out how to do this.  but here it is.

Public Class PrintForm
    Private Sub lstPrint_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstPrint.SelectedIndexChanged

    End Sub

    Private Sub btnAddPrint_Click(sender As Object, e As EventArgs) Handles btnAddPrint.Click


        While lstPrint.SelectedIndices.Count > 0
            MainForm.lstCart.Items.Add(lstPrint.Items(
            lstPrint.SelectedIndices(0)))
            lstPrint.Items.Remove(lstPrint.Items(
            lstPrint.SelectedIndices(0)))
        End While



    End Sub
End Class

[Rob Frank]

ok so i'm still on this for anyone who cares. I cannot get my numbers to populate in my labels. I just get zeros. I have inserted breakpoints and i can't figure this out....

main form

Public Class MainForm

    'declare variables

    Private Sub ToolStripMenuItem1_Click(sender As Object, e As EventArgs) Handles mnuFile.Click

    End Sub

    Private Sub frmMain_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub

    Public Sub mnuPrint_Click(sender As Object, e As EventArgs) Handles mnuPrint.Click
        'create an instance of the PrintForm

        'display the PrintForm
        frmPrint.Show()
        'add menu items to list box
        frmPrint.lstPrint.Items.Add("I Did It Your Way (Print)")
        frmPrint.lstPrint.Items.Add("The History of Scotland(Print)")
        frmPrint.lstPrint.Items.Add("Learn Calculus in One Day(Print)")
        frmPrint.lstPrint.Items.Add("Feel the Stress(Print)")

    End Sub

    Public Sub mnuAudio_Click(sender As Object, e As EventArgs) Handles mnuAudio.Click
        'create an instance of the AudioForm

        'display the AudioForm
        frmAudio.Show()
        'add menu items to list box
        frmAudio.lstAudio.Items.Add("Learn Calculus in One Day(Audio)")
        frmAudio.lstAudio.Items.Add("Relaxation Techniques(Audio)")
        frmAudio.lstAudio.Items.Add("The History of Scotland(Audio)")
        frmAudio.lstAudio.Items.Add("The Science of Body Language(Audio)")

    End Sub

    Private Sub mnuAbout_Click(sender As Object, e As EventArgs) Handles mnuAbout.Click
        'display a simple about box
        MessageBox.Show("Book Selector System Version 1.0")
    End Sub

    Public Sub lstCart_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstCart.Click

    End Sub

    Private Sub btnRemove_Click(sender As Object, e As EventArgs) Handles btnRemove.Click
        'loop to remove items from cart list box and add them to print list box
        If lstCart.SelectedItem.ToString.Contains("Print") Then
            While lstCart.SelectedIndices.Count > 0
                frmPrint.lstPrint.Items.Add(lstCart.Items(
                    lstCart.SelectedIndices(0)))
                lstCart.Items.Remove(lstCart.Items(
                    lstCart.SelectedIndices(0)))
            End While
            'loop to remove items from cart list box and add them to audio list box
        ElseIf lstCart.SelectedItem.ToString.Contains("Audio") Then
            While lstCart.SelectedItems.Count > 0
                frmAudio.lstAudio.Items.Add(lstCart.Items(
                    lstCart.SelectedIndices(0)))
                lstCart.Items.Remove(lstCart.Items(
                    lstCart.SelectedIndices(0)))
            End While
        Else
            MessageBox.Show("There is nothing to remove. ")
            calcSub()
            addItems()
        End If
        lblSub.Text = decSub.ToString("c")
        lblShipping.Text = decShipping.ToString("c")
        lblTax.Text = decTax.ToString("c")
        lblTotal.Text = decTotal.ToString("c")

    End Sub

    Private Sub mnuReset_Click(sender As Object, e As EventArgs) Handles mnuReset.Click
        'clears main form
        lstCart.Items.Clear()
        lblShipping.Text = ""
        lblSub.Text = ""
        lblTax.Text = ""
        lblTotal.Text = ""
    End Sub

    Private Sub mnuExit_Click(sender As Object, e As EventArgs) Handles mnuExit.Click
        'closes all forms
        Me.Close()
        frmAudio.Close()
        frmPrint.Close()
    End Sub

End Class

second form

Public Class frmPrint

    Private Sub lstPrint_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstPrint.SelectedIndexChanged

    End Sub

    Public Sub btnAddPrint_Click(sender As Object, e As EventArgs) Handles btnAddPrint.Click
        'removes items from print list box and adds them to cart list box

        While lstPrint.SelectedIndices.Count > 0
            MainForm.lstCart.Items.Add(lstPrint.Items(
            lstPrint.SelectedIndices(0)))
            lstPrint.Items.Remove(lstPrint.Items(
            lstPrint.SelectedIndices(0)))
        End While
        calcSub()
        addItems()

        MainForm.lblSub.Text = decSub.ToString("c")
        MainForm.lblShipping.Text = decShipping.ToString("c")
        MainForm.lblTax.Text = decTax.ToString("c")
        MainForm.lblTotal.Text = decTotal.ToString("c")

    End Sub

    Private Sub btnClosePrint_Click(sender As Object, e As EventArgs) Handles btnClosePrint.Click
        'closes the form
        Me.Close()
    End Sub

End Class

third form

Public Class frmAudio

    Private Sub lstAudio_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstAudio.SelectedIndexChanged

    End Sub

    Private Sub AudioForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub

    Private Sub btnAddAudio_Click(sender As Object, e As EventArgs) Handles btnAddAudio.Click
        While lstAudio.SelectedIndices.Count > 0
            MainForm.lstCart.Items.Add(lstAudio.Items(
            lstAudio.SelectedIndices(0)))
            lstAudio.Items.Remove(lstAudio.Items(
            lstAudio.SelectedIndices(0)))
        End While
        calcSub()
        addItems()

        MainForm.lblSub.Text = decSub.ToString("c")
        MainForm.lblShipping.Text = decShipping.ToString("c")
        MainForm.lblTax.Text = decTax.ToString("c")
        MainForm.lblTotal.Text = decTotal.ToString("c")
    End Sub

    Private Sub btnCloseAudio_Click(sender As Object, e As EventArgs) Handles btnCloseAudio.Click
        Me.Close()

    End Sub

End Class

and a module containing the variables and functions

Module CalcModule

    'declare constants
    Public Const decYourWayPrint As Decimal = 11.95D

    Public Const decScotPrint As Decimal = 14.5D
    Public Const decLearnPrint As Decimal = 29.95D
    Public Const decStressPrint As Decimal = 18.5D
    Public Const decLearnAudio As Decimal = 29.95D
    Public Const decRelaxAudio As Decimal = 11.5D
    Public Const decScotAudio As Decimal = 14.5D
    Public Const decBodyAudio As Decimal = 12.95D
    Public Const decTax_Rate As Decimal = 0.06D
    Public Const decShipping_Rate As Decimal = 2D
    Public intTotal As Integer
    Public decSub As Decimal
    Public decTax As Decimal = decSub * decTax_Rate
    Public decShipping As Decimal = intTotal * decShipping_Rate
    Public decTotal As Decimal = decSub + decTax + decShipping

    Public Function calcSub() As Decimal
        If MainForm.lstCart.Items.ToString.Contains("Your Way ") Then
            decSub += decYourWayPrint
        ElseIf MainForm.lstCart.Items.ToString.Contains("Scotland Print") Then
            decSub += decScotPrint
        ElseIf MainForm.lstCart.Items.ToString.Contains("Learn Print") Then
            decSub += decLearnPrint
        ElseIf MainForm.lstCart.Items.ToString.Contains("Stress Print") Then
            decSub += decStressPrint
        ElseIf MainForm.lstCart.Items.ToString.Contains("Learn Audio") Then
            decSub += decLearnAudio
        ElseIf MainForm.lstCart.Items.ToString.Contains("Relaxation Audio") Then
            decSub += decRelaxAudio
        ElseIf MainForm.lstCart.Items.ToString.Contains("Scotland Audio") Then
            decSub += decScotAudio
        ElseIf MainForm.lstCart.Items.ToString.Contains("Body Audio") Then
            decSub += decBodyAudio
        End If
        Return decSub
    End Function

    Public Function addItems() As Integer
        For Each i As String In MainForm.lstCart.Items
            If i.ToString.Contains("Print") Then
                intTotal += 1
            ElseIf i.ToString.Contains("Audio") Then
                intTotal += 1
            End If
        Next
        Return intTotal
    End Function

End Module

I'd really appreciate any help as always. One note I should be able to get a count going instead of using the for loop. but either way i can't make that work. I run the program and intTotal = 0 decSub=0 and so on. No errors are found. And sorry for the lack of comments. I should be doing them as i go but i've gotten so frustrated i've been deleting and changing stuff all over the place.

[Rob Frank]

well my problem is in my  module. my function calcSub() . I'm trying to search the cart items for my loop. however i have never done this before and it would appear that  using ".Contains" is not the correct way to go. It does not pick up anything in my cart items. I have tried

If MainForm.lstCart.Items.ToString.Contains("Your Way ") Then
            decSub += decYourWayPrint

and

If MainForm.lstCart.Items.Contains("Your Way ") Then
            decSub += decYourWayPrint

and

If MainForm.lstCart.Items.ToString.Contains("Your Way ") = True Then
            decSub += decYourWayPrint

can't make anything of that really do anything.