CODEWITHSUNDEEP
vb.netformsclass
Exn
Exn

Reputation: 809

How to pass data from one form to another using a class (VB.Net)

In my main program (form) I have two list boxes, one text box, and a button. When I pick two items in each list boxes and enter a number in the text box, it is suppsoed to be stocked in an array. I wanted to do this using a class. (I just asked a question about this, it works well now). The problem is I want to show the results in a different form. The code in my class looks like this:

Public Class Stocking


Public sale(3, 4) As Integer
Public numberSellers(3) As Integer
Public numberProducts(4) As Integer


Public Sub addItem(ByRef my_sellerListBox As ListBox, ByRef my_productListBox As ListBox, ByRef my_saleTextBox As TextBox)
    Dim sellerLineInteger As Integer
    Dim productColumnInteger As Integer

    sellerLineInteger = my_sellerListBox.SelectedIndex
    productColumnInteger = my_productListBox.SelectedIndex

    ' add in two dimensional array 
    If sellerLineInteger >= 0 And productColumnInteger >= 0 Then
        sale(sellerLineInteger, productColumnInteger) = Decimal.Parse(my_saleTextBox.Text)
    End If

    my_saleTextBox.Clear()
    my_saleTextBox.Focus()

    For sellerLineInteger = 0 To 3
        For productColumnInteger = 0 To 4
            numberSellers(sellerLineInteger) += sale(sellerLineInteger, productColumnInteger)
        Next productColumnInteger
    Next sellerLineInteger

End Sub
Public Sub showItems(ByRef my_label)

    my_label.Text = numberSellers(0).ToString 'using this as a test to see if it works for now


End Sub
End Class

My main form looks like this:

Public Class showForm

Public sale(3, 4) As Integer
Public numberSellers(3) As Integer
Public numberProducts(4) As Integer

Dim StockClass As New Stocking

    Public Sub addButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles addButton.Click

    StockClass.addItem(sellerListBox, producttListBox, saleTextBox)

End Sub

Public Sub SalesByMonthToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SalesByMonthToolStripMenuItem.Click

    saleForm.Show()

And in my second form, to show the results stocked in the array is:

Public Class saleForm

Dim StockClass As New Stocking

Public Sub saleForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    StockClass.showItems(Label00)
    'Only using one label as a test for now.

End Sub

End Class

End Sub

I tested it and tried to see if the results shows on the main form, it does. So I'm guessing the problem is because I use a different form. Also I think it might be because I call the class again in my different form and doesn't keep the data.

Upvotes: 1

Views: 7997

Answers (1)

Jason M. Batchelor
Jason M. Batchelor

Reputation: 2951

The problem is that your saleForm is instantiating a new Stocking object. You need to send the Stocking object that is created in your primary form to the new form, during the creation of saleForm, or you need to make the Stocking object in your main form publically available, perhaps through a property.

So, in your main form, you might have something like this:

Public StockClass As New Stocking

then, because it's not protected as a private variable, you could access it from your secondary form through something like 

showForm.StockClass.showItems(Label00)

The danger, of course, is that this tightly binds the two forms together. It would be better, in the long run, to learn how to send the StockClass that is populated in the first form to the second form during initialization, but I don't remember enough on WinForms development to help with that, sorry.

Upvotes: 1

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