Timer.elapsed event problem

Question

0.00/5 (No votes)

See more:

i stucked with a timer, can someone explain please how this event works? what to call in main form, to make this module start? I created a module called "Example", tried to make timer write in form1 label text "hello" every 2seconds, but when i start app nothing happens. Any help? Thanks. Im using WinForms

What I have tried:

Imports System.Timers
Public Module example
    Private aTimer As Timer
    Public Sub Main()

        ' Create a timer and set a two second interval.
        aTimer = New System.Timers.Timer()
        aTimer.Interval = 2000

        ' Hook up the Elapsed event for the timer.  
        AddHandler aTimer.Elapsed, AddressOf OnTimedEvent

        ' Have the timer fire repeated events (true is the default)
        aTimer.AutoReset = True

        ' Start the timer
        aTimer.Enabled = True

    End Sub
    Private Sub OnTimedEvent(source As Object, e As System.Timers.ElapsedEventArgs)
        Form1.Label1.Text = " hello"
    End Sub

End Module

Posted 4-Jul-17 15:03pm

JeezyWonder

Updated 4-Jul-17 15:47pm

v2

Add a Solution

2 solutions

Solution 1

Oops...

VB

' Start the timer
aTimer.Start

Posted 4-Jul-17 15:41pm

User 7407470

Updated 4-Jul-17 15:44pm

v2

Comments

Dave Kreskowiak 4-Jul-17 21:50pm

Not needed. Setting Enabled to True does the same thing.

[no name] 4-Jul-17 21:55pm

Yes, you're right. Sorry about that. Thanks.

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Dave Kreskowiak · Accepted Answer · 2017-07-04T15:47:00

It doesn't work because the Elapsed event is raised on a different thread[^] from the UI thread (startup). You cannot touch UI controls from anything other than the UI thread. In this case, you're going to have to Invoke a method on the UI thread to change the text in the TextBox.

VB.NET

Private aTimer As Timer = Nothing

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    aTimer = New Timer() With {
        .Interval = 2000
    }

    ' Hook up the Elapsed event for the timer.
    AddHandler aTimer.Elapsed, AddressOf OnTimedEvent

    ' Have the timer fire repeated events (true is the default)
    aTimer.AutoReset = True

    ' Start the timer
    aTimer.Enabled = True
End Sub

Private Sub OnTimedEvent(source As Object, e As System.Timers.ElapsedEventArgs)
    SetTextBoxText("Elapsed")
End Sub

Private Sub SetTextBoxText(message As String)
    If Me.InvokeRequired Then
        Invoke(Sub()
                   SetTextBoxText(message)
               End Sub)
    Else
        TextBox1.Text = "Elapsed"
    End If
End Sub