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How to: Create an Event and Handler (Visual Basic)

This example defines an event, TimeExpired, and an event handler, HandleTimeExpired, and uses the AddHandler statement to associate them.

Public Event TimeExpired(ByVal Status As String)
Public Sub HandleTimeExpired(ByVal Status As String)
    ' Perform desired processing for when time has expired.
    MsgBox("HandleTimeExpired caught the TimeExpired event" & _
           vbCrLf & "Status = " & Status)
End Sub 
Public Sub SetUpEventHandler()
    AddHandler TimeExpired, AddressOf HandleTimeExpired
End Sub
Public Event TimeExpired(ByVal Status As String)
Public Sub HandleTimeExpired(ByVal Status As String)
    ' Perform desired processing for when time has expired.
    MsgBox("HandleTimeExpired caught the TimeExpired event" & _
           vbCrLf & "Status = " & Status)
End Sub 
Public Sub SetUpEventHandler()
    AddHandler TimeExpired, AddressOf HandleTimeExpired
End Sub

This example requires:

  • Access to the members of the System namespace. Add an Imports statement if you are not fully qualifying member names in your code. For more information, see Imports Statement (.NET Namespace and Type).

  • The Event statement to be at class level and not inside any procedure.

  • The Event statement and both procedures (HandleTimeExpired and SetUpEventHandler) to be defined in the same class or module. Otherwise the AddHandler statement must qualify the event and the handler to the objects in which they are defined.

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