Programmatically change the startup form on application launch? - vb.net

Question

Can I programmatically change the startup form on application launch in VB.Net?

Answer 1

Sure you can!
In your Project Properties, set Startup Object to Sub Main, and make sure that there's a Public Sub Main method somewhere in your application. A separate startup class may be a good idea:
Public Class myStartupClass
''' <summary>
''' This is the method that will be run when the application loads,
''' because Project Properties, Startup Object is set to SubMain
''' </summary>
''' <remarks>
''' </remarks>
''' --------------------------------------------------------------------------------
Public Shared Sub Main()
'The form that we will end up showing
Dim formToShow As System.Windows.Forms.Form = Nothing
'The determiner as to which form to show
Dim myMood As String = "Happy"
'Choose the appropriate form
Select Case myMood
Case "Happy"
formToShow = New Form1
Case Else
formToShow = New Form2
End Select
'Show the form, and keep it open until it's explicitly closed.
formToShow.ShowDialog()
End Sub
End Class

Answer 2

In a "Windows Forms Application", created under VB 2010 Express, you can do the following in ApplicationEvents.vb:
Partial Friend Class MyApplication
Private Sub MyApplication_Startup(ByVal sender As Object, ByVal e As Microsoft.VisualBasic.ApplicationServices.StartupEventArgs) Handles Me.Startup
'Select the form of your choice
My.Application.MainForm = Any_Form_You_like
End Sub
End Class

Answer 3

This is the approach I use which effectively starts a form like a normal an application entry point.
Public Sub Main()
Dim value As String = Trim(Environment.CommandLine)
Dim f As Form
Select Case value
Case "a"
f = New frmTextEdit
Case "b"
f = New frmListDialog
Case "c"
f = New frmSuggestion
Case Else
Throw New Exception("Unsupported startup form option")
End Select
Application.Run(f)
End Sub

Answer 4

The right method is change MainForm of project.
Open ApplicationsEvents.vb
At ApplicationStart.vb use:
Private Sub MyApplication_Startup(sender As Object, e As StartupEventArgs) Handles Me.Startup
Dim formToShow As System.Windows.Forms.Form = Nothing
Dim AM_PM as String = "AM"
Select Case
Case "AM"
Me.MainForm = frmBefore
Case "PM"
Me.MainForm = frmAfter
End Select
MainForm.Show()
End Sub
That's is.