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VB.NET: How to Handle Events of Objects inside a Generic List

Hello,
i developed code that works fine so far but now i would like to upgrade from a single element to multiple elements using a generic list (that´s what i thought of, maybe you know something better) so i changed my codeing from

Protected WithEvents MyObject
to
Protected WithEvents myList As List(Of MyObject)

i used to handle the CurrentChanged event of MyObject

so i thought i could do something lilke this

change from
Private Sub _CurrentChanged() Handles MyObject.CurrentChanged
to
Private Sub _CurrentChanged() Handles MyList.ITEM.CurrentChanged

which does not work, and i did not yet find a solution for my simple problem, can anyone help ?

Kind Regards Frank

kaufmed

When you add events to your list, you have to add handlers to them also. An example is below. Also, I think the "WithEvents" clause is meaningless for a List, but I'd love to know otherwise :)

Protected myList As List(Of MyObject)

...

' create temp var
Dim obj As New MyObject()
' add the handler
AddHandler(obj.CurrentChanged, AddressOf _CurrentChanged)
' add to list
Me.myList.Add(obj)

...

Private Sub _CurrentChanged()

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kaufmed

>> When you add events to your list,

That should say, "when you add *objects* to your list..."

Mike Tomlinson

So typically you'd "wire up" all the dynamic instances with AddHandler() as outlined by kaufmed...

...does the CurrentChanged() event of MyObject provide a "sender" or "source" parameter so you can distinguish which instance fired the event?

For instance, most .Net events have a "sender" parameter tells which button fired the event:

Public Class Form1

    Private Buttons As New List(Of Button)

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        For i As Integer = 1 To 5
            Dim btn As New Button
            btn.Text = "Button #" & i
            AddHandler btn.Click, AddressOf btn_Click
            FlowLayoutPanel1.Controls.Add(btn)
            Buttons.Add(btn)
        Next
    End Sub

    Private Sub btn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
        Dim btn As Button = CType(sender, Button)
        MessageBox.Show("You clicked on: " & btn.Text)
    End Sub

End Class

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kaufmed

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michelsf

ASKER

Thank you guys works fine !!!