VB - Pass Variables/String to another Form and dis

Question

I have 2 forms, formOrder and formOrderSummary.

On formOrder there are 3 buttons and a listView1. btnVanilla, btnChocolate and btnNextPage and listview1

On formOrderSummary there is a listView2.

Each time Vanilla or Chocolate is clicked it will add it to the listview.

What I'm trying to do is get the listview1 on formOrder to show in listviewOrder on formOrderSummary. Currently I got it working if the listview is in the same form but I can't seem to do it if the listview is in a different form.

There is a screenshot below which visualises what I mean

formOrder

Public Class formOrder

Dim frm2 As New formOrderSummary
Public vanillaCount As Integer
Public chocolateCount As Integer
Public mynumber As Double

Private Sub btnVanilla_Click(sender As Object, e As EventArgs) Handles btnVanilla.Click

    Me.vanillaCount = Me.vanillaCount + 1
    Dim str(3) As String
    Dim item As ListViewItem

    str(0) = "Vanilla"
    str(1) = Me.vanillaCount.ToString()
    mynumber = str(1) * 1
    str(2) = mynumber.ToString("C")

    Dim WholeString As String = str(0)

    item = New ListViewItem(str)
    For maindish As Integer = 0 To Me.ListView1.Items.Count - 1


        If (Me.ListView1.Items(maindish).ToString = "ListViewItem: {" + WholeString + "}") Then
            Me.ListView1.Items.RemoveAt(maindish)
            Me.ListView1.Items.Add(item)

            Return
        End If
    Next

    Me.ListView1.Items.Add(item)

End Sub

Private Sub BtnChocolate_Click(sender As Object, e As EventArgs) Handles b btnChocolate.Click

    Me.chocolateCount = Me.chocolateCount + 1
    Dim str(3) As String
    Dim item As ListViewItem

    str(0) = "Chocolate"
    str(1) = Me.chocolateCount.ToString()
    mynumber = str(1) * 1.5
    str(2) = mynumber.ToString("C")

    Dim WholeString As String = str(0)

    item = New ListViewItem(str)
    For maindish As Integer = 0 To Me.ListView1.Items.Count - 1


        If (Me.ListView1.Items(maindish).ToString = "ListViewItem: {" + WholeString + "}") Then
            Me.ListView1.Items.RemoveAt(maindish)
            Me.ListView1.Items.Add(item)

            Return
        End If
    Next

    Me.ListView1.Items.Add(item)

End Sub

Private Sub btnConfirm_Click(sender As Object, e As EventArgs) Handles btnConfirm.Click

    frm2.Show()
    Me.Hide()
End Sub

End Class

FormOrderSummary

Public Class formOrderSummary

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


    End Sub
End Class

Answer 1

Forms are just classes, it says so at the top of all of them:

Public Class formOrder 

so, you can add all the methods or properties you'd like. All you really need to do is create a method (sub) to pass the order to. The bigger issue is how do you pass 2 things (2 cones) in one method? What if the Ice Creame Shoppe offered waffle cones, sprinkles, flavored shells or other extras?

Wouldn't it be great if there was a way to keep the data together and organized? There is:

Public Class IceCream

    Public Enum IceCreamFlavors
        Vanilla
        Chocolate
        Strawberry
    End Enum

    Public Property Flavor As IceCreamFlavors
    Public Property Sprinkles As Boolean
    Public Property Scoops As Int32

    Public Sub New()
        Scoops = 1
    End Sub

    Public ReadOnly Property Cost As Decimal
        Get
            Return GetCost()
        End Get
    End Property

    ' just because I dont like a lot of code in getters
    Private Function GetCost() As Decimal
        Dim price As Decimal = 0

        Select Case Flavor
            Case IceCreamFlavors.Chocolate
                price = 0.75D
            Case IceCreamFlavors.Vanilla
                price = 0.65D
            Case IceCreamFlavors.Strawberry
                price = 55D
                ' coming soon: Rocky Road!
        End Select

        Dim temp = (Scoops * price)

        If Sprinkles Then
            temp += 0.25D
        End If
        Return temp
    End Function
End Class

Ok, that will hold the info for one cone. Notice how it contains everything related to a cone item, even pricing. It is easy to make it more complex such as WaffleCones, Chocolate shell etc without adding lots of loose variables in your form.

We also will need a way to hold several of them. I know what you are thinking: array. Dont go there. A List(of IceCream) is even easier to use than an array.

Create Order

Private cones As New List(Of IceCream)   ' will only hold icecream items
...
Dim item = New IceCream
item.Flavor = IceCream.IceCreamFlavors.Chocolate
item.Sprinkles = False
item.Scoops = 2
cones.Add(item)

The block creates a new Icecream item, then sets the various attributes, then finally adds it to the list. Notice how I did not have to tell the List how big to be?

item = New IceCream
item.Flavor = IceCream.IceCreamFlavors.Vanilla
item.Sprinkles = True
cones.Add(item)

You access the info much the same way: Dim thisCost = item.Cost

The IceCream class defaults to 1 scoop, so you only have to set that when it is not one scoop. You could add other defaults.

Pass the Data

Now, on the order summary form create a method to accept the data:

Public Sub SummaryData(order As List(Of IceCream))

   ' post items to listview
   'e.g.: flavor = order(0).Flavor.ToString()
End Sub

If you want to add to it item by item, declare it to take one item:

Public Sub SummaryData(orderItem as IceCream)

(A problem will arise when you want to remove one). To pass the data:

frmSummaryINSTANCE.SummaryData(cones)

Tip: An even easier method is to use use a DataGridView.

dgv.DataSource = order

The DataGridView will create the columns and display the property data automagically.

You could of course use this without a Class or List by changing the arguments, but it gets wordy and dense as the number and type of arguments increases.

Form Instances
Once you have the data organized properly it becomes pretty easy to do whatever you want. Note: This assumes you are using form instances. That is, rather than:

formOrderSummary.SummaryData(cones)

You do something like this:

Dim frmSumm As New formOrderSummary()
frmSumm.SummaryData(cones)

As noted, forms are classes and the proper way to use them is to create an instance of one (just like in C#). If you are not doing that now, it is something else to learn right away.

You might also want to see: Five Minute Guide to Classes and Lists