Hello

I am a novice programmer who is doing an Open University [UK] degree level unit [for fun] on object oriented programming with VB Express Edition 2008.

I am trying to get my head around a number of ideas right now, the main ones at present being:
Constructors, what do they do, how, when and where to use them.

MY PROGRAM

I have a very small program with one form that allows me to populate a list and then to see those items appear in a list box on a form.

The form's controls consist of :

addNewNumberButton – please see the code  below.

addNewNumberTextBox: where I type in a string, in this case a number but it could be any string , to be added to the list, and then to the list box on the form.

 
numberListBox where the strings I type in to addNewNumberTextBox appear.

Here is the form’s code:

Public Class Form1
    Private numberList As List(Of String)
    Public Sub New()
        numberList = New List(Of String)

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

        ' Add any initialization after the InitializeComponent() call.

    End Sub

    Private Sub addNewNumberButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles addNewNumberButton.Click

        numberList.Add(addNewNumberTextBox.Text)
        addNewNumberTextBox.Clear()
        addNewNumberTextBox.Focus()
        updateView()

    End Sub

    Private Sub updateView()
        numberListBox.Items.Clear()
        For Each digit As String In numberList
            numberListBox.Items.Add(digit)

        Next
    End Sub
End Class

I also have an empty class called Lists_AddNumber.

MY FIRST PROBLEM

What I want to do is to use the class Lists_AddNumber to contain the code [that currently operates in the form’s code] which sets up a list to accept strings in exactly the same way that the form’s code does.

I would be grateful for an idiot-proof solution to this problem.

MY SECOND PROBLEM

Can anyone please give me some absolutely elementary guidance as to

1. What a constructor is [in VB 2008] and what does it do?
2. Where do you use it – in the form file or in a separate class file?
3. What is the syntax of a constructor?

Best wishes to all you clever folks out there.

Hope that you can point me in the right direction.

Many thanks.

Bob Dade