Raising an event in .net example

Question

I am trying to create a basic example of raising an event in vb.net, and I am hoping that by studying it thoroughly I can upgrade the way my system receives data from serial port.

Right now I have a system that receives the incoming data from serial port via timers, the problem is there are certain events in a system that conflicts in my timer. Because of this I am planning to change the way I received the data from serial ports, instead of timer I want to use vb.net raiseevent.

Unfortunately I can't find a simple example on how to use this event, by searching thoroughly I saw the MSDN's post about this topic and it is here. So, how do I use this example? I tried using it below like that

Public Event TimeExpired(ByVal Status As String)
Public Sub RaiseTimeExpiredEvent()
    RaiseEvent TimeExpired("Your time has run out")
    MessageBox.Show(TimeExpired())
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    RaiseTimeExpiredEvent()
End Sub

It's not working working, the error is

Error 1 'Public Event TimeExpired(Status As String)' is an event, and cannot be called directly. Use a 'RaiseEvent' statement to raise an event. C:\Users\Cary\Desktop\Projects\Testing\Testing\Testing\Form1.vb 5 25 Testing

Because of that error I tried to do it like this

Class Form1
Public Event TimeExpired(ByVal Status As String)
Public Sub RaiseTimeExpiredEvent()
    RaiseEvent TimeExpired("Your time has run out")
    MessageBox.Show(TimeExpired())

End Sub


Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    RaiseEvent TimeExpired()
End Sub

End Class

But the error states

Error 2 Argument not specified for parameter 'Status' of 'Public Event TimeExpired(Status As String)'. C:\Users\Cary\Desktop\Projects\Testing\Testing\Testing\Form1.vb 11 9 Testing

Answer 1

Are you using Visual Studio ? If yes, you can try to display the Error List. For that, click View, and Error List.

Class Form1

    Public Event TimeExpired(Status As String)

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        RaiseEvent TimeExpired("Your time has run out")
    End Sub

End Class

To handle the event, you can add this :

Private Sub HandleTimeExpired(Status As String) Handles Me.TimeExpired
    MsgBox(Status)
End Sub

Here is the full code :

Class Form1

    Public Event TimeExpired(Status As String)

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        RaiseEvent TimeExpired("Your time has run out")
    End Sub

    Public Sub OnTimeExpired(Status As String) Handles Me.TimeExpired
        MsgBox(Status)
    End Sub

End Class

Edit :

If you wanna move the raising of event in a module, you can't. You have to add it in a class. See this link.

Example of Class1 (you should rename it...) :

Public Class Class1

    Private Event TimeExpired(Status As String)

    Public Sub OnTimeExpired(Status As String)
        RaiseEvent TimeExpired(Status)
    End Sub

    Private Sub HandleTimeExpired(Status As String) Handles Me.TimeExpired
       MsgBox(Status)
    End Sub

End Class

And to use it, you have to declare it WithEvents in your Form1 :

Public Class Form1

    Dim WithEvents Class1 As New Class1

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Class1.OnTimeExpired("Your time has run out")
    End Sub

End Class