Question

At first I tried this:

Public Class frmWait

Public Sub New(ByVal uWindowText As String, ByVal uInfoText As String)

    Me.Text = uWindowText
    Me.lblInfoText.Text = uInfoText

End Sub

End Class

But when I initiated the form like this

            Dim wait As New frmWait("blah", "blah")
            wait.Show()

… it told me “NullReference Exception” at this line:

Me.lblInfoText.Text = uInfoText

Settings the form’s text worked fine.
Okay, I subspected the label was just not created yet when I tried to set the text.

Then I tried the following. I stored the texts in a variable and wanted to set them when the controls have been created. I thought “Form_Load” was a good event for that:

Public Class frmWait

Private m_sWindowText As String = ""
Private m_sInfoText As String = ""


Public Sub New(ByVal uWindowText As String, ByVal uInfoText As String)

    'we can not set the texts right away because lblInfo does not seem to exist yet

    m_sWindowText = uWindowText
    m_sInfoText = uInfoText

End Sub

Private Sub frmWait_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    Me.Text = m_sWindowText
    Me.lblInfoText.Text = m_sInfoText

End Sub

End Class

But it threw the same error.
Ehhhhh, when exactely can I set the control’s text?
Did I make any beginner’s mistake?

Answer 1

Don’t delete what the designer does 🙂 It’s trying to help you. When you Create the

Public Sub New(...)

on a form, it will automatically put in :

Public Sub New()

    ' This call is required by the designer.
    InitializeComponent()

    ' Add any initialization after the InitializeComponent() call.

End Sub

The InitializeComponent() is required to get the form ready for you to work with it.