multiple instances of an app. 2

[VBakias]

How can i prevent a user of my application from running the app more than one times. So if he double clicks again the app: msgbox("app is already launched!") + application.exit()

?

 

[earthandfire]

Use System.Diagnostics.Process to check to see if there is more than one instance of your program running. One way to do this and to avoid having your UI show would be to have a Sub Main, which checks for another instance of your program, terminating with MessageBox if it does and starting your program with Application.Run(New MainForm) if it doesn't

Hope this helps.

 

[chrissie1]

E&F do you need a module for that?

Christiaan Baes
Belgium

If you want to get an answer read this FAQ faq796-2540
There's no such thing as a winnable war - Sting

 

[chrissie1]

And here they recommend

http://www.vbcity.com/forums/faq.asp?fid=30&cat=General&#TID25519

this

Imports System.Threading 

Module modMain 
    Public mtx As Mutex 

    Public Sub Main() 

        Dim bCreated As Boolean 
        mtx = New Mutex(False, "SingleInstanceApp", bCreated) 
        If bCreated = True Then 


                Application.Run(New frmMain) 
        Else 
            End 
        End If 

    End Sub 
End Module

Christiaan Baes
Belgium

If you want to get an answer read this FAQ faq796-2540
There's no such thing as a winnable war - Sting

 

[earthandfire]

Just for you Chrissie

Public Class Startup

  Public Shared Sub Main()

    Dim splash As New Splash
    splash.Show()
    Dim loResult As DialogResult
    Dim lo As New LogOn
    splash.Label1.Text = "Logging on ..."
    splash.Refresh()
    Threading.Thread.CurrentThread.Sleep(1000)
    lo.ShowDialog()
    loResult = lo.DialogResult
    lo.Dispose()
    If loResult = DialogResult.OK Then
      splash.Label1.Text = "Log On successful"
    Else
      splash.Label1.Text = "Log on failed"
    End If
    splash.Refresh()
    Threading.Thread.CurrentThread.Sleep(1000)
    splash.Dispose()
    Application.Run(New ClassLibrary1.Form1)
  End Sub

End Class

and I thought Mutexes died with DOS!!! From dim distant memory I think I used to use them to lock critical non-re-entrant sections.

 

[chrissie1]

E&F I think that your most important code is in lo could we have that too for future reference

Christiaan Baes
Belgium

If you want to get an answer read this FAQ faq796-2540
There's no such thing as a winnable war - Sting

 

[earthandfire]

Got to keep some trade secrets Chrissie

 

[ca8msm]

I use the method decribed by E&F e.g

    Private Function PrevInstance() As Boolean
        If Diagnostics.Process.GetProcessesByName(Diagnostics.Process.GetCurrentProcess.ProcessName).Length > 1 Then
            Return True
        Else
            Return False
        End If
    End Function

but that's a good alternative that Chrissie points out (something which I may start to use instead).


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[earthandfire]

ca8msm, I actually use a slight variation of that - to force the "OtherMe" to become active. This is because I've assumed that the user wants to use the program.

I'll need to look in detail at both your version and chrissie's version to see if I can use them, because they would greatly simplify my code:

  Public Sub Main()

    'Prevent more than one instance from running at a time
    Dim OtherMe As Integer
    Dim MeCount As Integer = 0
    For Each p As Process In GetProcesses()
      If p.ProcessName = ApplicationName Then
        MeCount += 1
        If Not (p Is GetCurrentProcess()) Then
          OtherMe = p.Id
        End If
      End If
    Next
    If MeCount = 1 Then
      Options = New OptionsClass
      Dim HasCommandLine As Boolean
      Dim CommandLineOK As Boolean = EvalCommandLine(HasCommandLine)
      If CommandLineOK Then
        If HasCommandLine Then
          If Options.SaveSettings(True) Then
            ShowMessage _
                ("Re-start and logon as the default user", MB.MsgBtns.OK, MB.MsgIcon.Info)
          Else
            ShowMessage _
                ("Unable to create options file", MB.MsgBtns.OK, MB.MsgIcon.Error)
          End If
        Else
          Dim ok As Boolean
          Dim formSplash As New SplashScreenForm
          formSplash.Show()
          Application.DoEvents()
          ok = Options.LoadSettings()
          If ok Then
            ok = Logon()
          Else
            ShowMessage _
                        ("Unable to properly initialise.", MB.MsgBtns.OK, MB.MsgIcon.Error)
          End If
          formSplash.Close()
          If ok Then Application.Run(New MainForm)
        End If
      Else
        ShowMessage _
            ("Invalid startup parameter(s)", MB.MsgBtns.OK, MB.MsgIcon.Error)
      End If
    Else
      ShowMessage _
        ("You can only run me once at a time", MB.MsgBtns.OK, MB.MsgIcon.Error)
      AppActivate(OtherMe)
    End If
    Application.Exit()

  End Sub