How do I fire an event in VB.NET code?

问题

I have a form that has a start button (to allow users to run the processes over and over if they wish), and I want to send a btnStart.Click event when the form loads, so that the processes start automatically.

I have the following function for the btnStart.Click event, but how do I actually tell Visual Basic 'Pretend someone has clicked the button and fire this event'?

I've tried going very simple, which essentially works. However, Visual Studio gives me a warning Variable 'sender' is used before it has been assigned a value, so I'm guessing this is not really the way to do it:

Dim sender As Object
btnStart_Click(sender, New EventArgs())

I have also tried using RaiseEvent btnStart.Click, but that gives the following error:

'btnStart' is not an event of 'MyProject.MyFormClass

Code

Imports System.ComponentModel

Partial Public Class frmProgress

    Private bw As BackgroundWorker = New BackgroundWorker

    Public Sub New()

        InitializeComponent()

        ' Set up the BackgroundWorker
        bw.WorkerReportsProgress = True
        bw.WorkerSupportsCancellation = True
        AddHandler bw.DoWork, AddressOf bw_DoWork
        AddHandler bw.ProgressChanged, AddressOf bw_ProgressChanged
        AddHandler bw.RunWorkerCompleted, AddressOf bw_RunWorkerCompleted

        ' Fire the 'btnStart.click' event when the form loads
        Dim sender As Object
        btnStart_Click(sender, New EventArgs())

    End Sub

    Private Sub btnStart_Click(sender As Object, e As EventArgs) Handles btnStart.Click

        If Not bw.IsBusy = True Then

            ' Enable the 'More >>' button on the form, as there will now be details for users to view
            Me.btnMore.Enabled = True

            ' Update the form control settings so that they correctly formatted when the processing starts
            set_form_on_start()

            bw.RunWorkerAsync()

        End If

    End Sub

    ' Other functions exist here

End Class

回答1:

You should send a button as sender into the event handler:

btnStart_Click(btnStart, New EventArgs())

回答2:

Steps in involved in raising an event is as follows,

Public Event ForceManualStep As EventHandler
RaiseEvent ForceManualStep(Me, EventArgs.Empty)
AddHandler ForceManualStep, AddressOf ManualStepCompletion

Private Sub ManualStepCompletion(sender As Object, e As EventArgs)        


End Sub

So in your case, it should be as below,

btnStart_Click(btnStart, EventArgs.Empty)

回答3:

You are trying to implement a bad idea. Actually, you have to make a subroutine to accomplish these kind of tasks.

Private Sub btnStart_Click(sender As Object, e As EventArgs) Handles btnStart.Click

      call SeparateSubroutine()

End Sub

private sub SeparateSubroutine()

   'Your code here.

End Sub

And then whereever you want to call the btnStart's click event, just call that SeparateSubroutine. This should be a correct way in your case.

回答4:

Just Call

btnStart.PerformClick()

来源：https://stackoverflow.com/questions/15831599/how-do-i-fire-an-event-in-vb-net-code

标签

vb.net

events

raiseevent