Event Handler and Delegate

Question

1.00/5 (1 vote)

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VS2005

Hello all,

i have a question for the event handler, i'm really weak in this event handler/delegate.
normal event handler like example 1 still ok for me,

example 1 :

VB

private abc as eventhandler
private sub MethodTest()
   addhandler me.abc, addressof Method1
End Sub

but i see some code do like below example 2:

example 2 :

VB

Private ZZZ As System.EventHandler = Nothing

private sub Method999()
   Me.ZZZ = New EventHandler(AddressOf Method1)
   <big>AddHandler me.AnotherEvent, me.ZZZ</big>
End Sub

private sub Method1(byval sender as object, byval e as eventArgs)
   'do something
End Sub

as what i know the example 1 and example 2 will perform the same function.
im not really understand how to use the code do like this.
hope somebody help me for this.

Posted 17-Jan-12 21:48pm

jonaschu

Updated 29-Jan-12 13:57pm

v4

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Comments

Sergey Alexandrovich Kryukov 18-Jan-12 4:30am

???

2 solutions

Solution 1

This is what I have done in the past. I hope this helps you.

A separate class that does something.

VB

Public Class clsClassEvents
Event ReportFeedback(strMessage As String)

Public Sub DoSomething()
RaiseEvent ReportFeedback("I did something!")
End Sub
End Class

In my main form I declared my class as follows.

VB

Private WithEvents myFeedback As New clsClassEvents()

Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
myFeedback.DoSomething()
End Sub

'Every time you call myFeedback.DoSomething() this Sub will be triggered.
Private Sub myFeedback_ReportFeedback(strMessage As String) Handles myFeedback.ReportFeedback
Me.Text = strMessage
End Sub

Let me know if this helps.

Posted 18-Jan-12 8:46am

Clark Kent123

Updated 19-Jan-12 7:46am

v2

Comments

Idle_Force 19-Jan-12 13:41pm

'Every time you call myFeedback.DoSomething() this Sub will be triggered.
Private Sub clsClassEvents_myFeedback (strMessage As String) Handles clsClassEvents.ReportFeedback '<-fixed this line, correct event name
Me.Text = strMessage
End Sub

Clark Kent123 19-Jan-12 13:48pm

Thanks I have updated my solution.

jonaschu 29-Jan-12 19:55pm

bro, thanks for your suggestion. i know for this method.. this method normally i use as a static event handler.. i just don't know what is the different from example 1 and example 2 code i paste on the top.

Clark Kent123 30-Jan-12 13:56pm

No problem. I encourage you to check the link Simon_Whale posted (Solution #2). The answer is found there.

Check the section on "Associating Events with Event Handlers"
http://msdn.microsoft.com/en-us/library/2z7x8ys3%28v=vs.71%29.aspx

Finally, I would like to encourage you to vote if either or both of us have answered your question. So it can be closed or rephrase your question.

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Simon_Whale · Accepted Answer · 2012-01-30T01:05:00

Solution 2

MSDN: EventHandler Delegate[^]

From reading the above article there is no technical difference between them except you are creating a eventhandler variable and assigning the addressof statement to that rather than the addhandler statement.

hope that makes sense

Posted 30-Jan-12 1:05am

Simon_Whale