What are events?
As compared to the delegates events works with source and listener methodology. So the listeners who are interested in receiving few events they subscribe to the source. Once this subscription is completed the source raises events to its entire listener when required. One source can have many listeners. In the sample given below class "ClsWithEvents" is an event source class, which has a event "EventAddString()". Now the listeners who are interested in receiving these events they can subscribe to this event. In the class "FrmWithEvents" you can see they handle clause which is associated with the "mobjClsWithEvents" objects.
Public Class ClsWithEvents
Event EventAddString(ByVal Value As String) Public Sub AddString()
RaiseEvent EventAddString("String added by Event") End Sub
Public Class FrmWithEvents
Private WithEvents mobjClsWithEvents As New ClsWithEvents() Private Sub FrmWithEvents_Load(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles MyBase.Load
Private Sub mobjClsWithEvents_EventAddString(ByVal Value As
String) Handles mobjClsWithEvents.EventAddString
LstData.Items.Add(Value) End Sub
Private Sub CmdRunEvents_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CmdRunEvents.Click
mobjClsWithEvents.AddString() End Sub
Figure:-Events in action