VB.NET Class with no constructor (no new instance can be declared) - vb.net

Question

I'm making my own message box class (called MessageBoxC, whatever), and like System.Windows.Forms.MessageBox, I want to make my class with no constructors and no possibility to declare a new instance of it.
E.g.:
Public Class MessageBoxC
Public Overloads Sub Show(ByVal message As String)
Me.Message = message
ProcessData() '(*)
Me.ShowDialog()
End Sub
End Class
Public Class Form1
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
System.Windows.Forms.MessageBox.Show("Hello World!") 'works fine
MessageBoxC.Show("Hello World!") 'works fine
Dim msgBox As New System.Windows.Forms.MessageBox 'and you'll get an error message here (**)
Dim msgBoxC As New MessageBoxC 'no error message
End Sub
End Class
(*) Not important. It just calculates text size (width and height in pixels) to correct form size if needed and the corresponding label gets value of Me.Message property.
(**) This one is what I mean. You cannot make a new instance of a MessageBox class, you'll get following error-message: "Type System.Windows.Forms.MessageBox has no constructors."
Well, my class has also no constructors, but it's possible to declare an instance of it. What's the trick here?
Thanks a lot!
Solved. Thanks to OneFineDay.
Public Class MessageBoxC
Private Sub New()
'Empty
End Sub
Public Overloads Shared Function Show(ByVal message As String) As System.Windows.Forms.DialogResult
Return Show(message, Constants.MyAppName, Constants.messageTitle, MessageBoxCButtons.OK, MessageBoxCIcon.Undefined)
End Function
Public Overloads Shared Function Show(ByVal message As String, _
ByVal caption As String, _
ByVal title As String, _
ByVal buttons As Library.MessageBoxCButtons, _
ByVal icon As Library.MessageBoxCIcon) As System.Windows.Forms.DialogResult
Dim msgBoxC As New CBox(message, caption, title, buttons, icon)
msgBoxC.ShowDialog()
Return msgBoxC.DialogResult
End Function
Private Class CBox
Inherits System.Windows.Forms.Form
Sub New(ByVal message As String, _
ByVal caption As String, _
ByVal title As String, _
ByVal buttons As Library.MessageBoxCButtons, _
ByVal icon As Library.MessageBoxCIcon)
MyBase.New()
InitializeComponent()
Me.Message = message
Me.Text = caption
Me.Title = title
Me.Buttons = buttons
Me.Icon64 = icon
Me.OptimizeMe()
End Sub
End Class
End Class
Public Class Form1
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
Dim dialogResult As New DialogResult
dialogResult = MessageBoxC.Show("This is a simple message.")
MessageBox.Show(dialogResult.ToString)
End Sub
End Class

Answer 1

If you don't declare any constructors, a default constructor is automatically created (this is a public constructor with no parameters).
To prevent anyone creating an instance of your class, you can create a private constructor, like so:
Public Class MessageBoxC
Private Sub New()
' Prevents anyone creating an instance of this class.
End Sub
End Class
Note that your Show method will need to be declared Shared, otherwise you won't be able to call it. In fact, it would need to be Shared, even with the code you provided.

Answer 2

Here is one way to hide the constructor - mainly because the class in question is not accessible.
Public Class Form1
Private Sub meLoad() Handles Me.Load
'Usage
FooBar.Show("Hi")
End Sub
'...
End Class
Public Class FooBar
Private Sub New()
End Sub
Public Shared Sub Show(message As String)
Dim mbc As New MessageBoxC(message)
mbc.ShowDialog()
End Sub
'MessageBoxC is not exposed outside of Foobar which is the entry point
Private Class MessageBoxC : Inherits Form
'define cTor's as needed
Public Sub New(message As String)
Me.Text = message
End Sub
'define content
End Class
End Class