[RESOLVED] Problem with Thread

[helderjsd]

Hi everyone,

In one application, I need use 4 simultaneous threads.

When the threads finished, I need to update the text of a TextBox.

So, I create 4 Textbox, and I wanna the threads change the text to FINISHED.
Each thread change one distinct TB.

I use this "example" code:

    Dim Terminados As Integer = 0

    Private Sub frmEnviarMensagem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Timer1.Enabled = True
        Timer1.Start()
        Dim t1 As New Thread(AddressOf tarefa1)
        Dim t2 As New Thread(AddressOf tarefa2)
        Dim t3 As New Thread(AddressOf tarefa3)
        Dim t4 As New Thread(AddressOf tarefa4)
        t1.Start()
        t2.Start()
        t3.Start()
        t4.Start()

    End Sub

    Private Sub tarefa1()
        tbPlaca1.Enabled = True
        tbQtd1.Enabled = True
        tbPlaca1.Text = "TERMINADO..."
        Terminados = Terminados + 1

    End Sub

The problem is, I have an error in the red lines.

The error is:
INVALIDOPERATIONEXCEPTION
"Cross-Thread operation not valid: Control tbPlaca1 Accessed from a thread other than the thread it was created on."

I don't use cross threading. Each TB only was accessed for the correspondent thread, and for the "main program".

How can I do this??

Thnak You

[.paul.]

you need to invoke your controls on each new thread. here's an example:

Public Class Form1
 
    Dim Terminados As Integer = 0
 
    Private Sub frmEnviarMensagem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'Timer1.Enabled = True
        'Timer1.Start()
        Dim t1 As New Threading.Thread(AddressOf tarefa1)
        'Dim t2 As New Thread(AddressOf tarefa2)
        'Dim t3 As New Thread(AddressOf tarefa3)
        'Dim t4 As New Thread(AddressOf tarefa4)
        t1.Start()
        't2.Start()
        't3.Start()
        't4.Start()
 
    End Sub
 
    Private Sub tarefa1()
        enableTextbox(tbPlaca1)
        enableTextbox(tbQtd1)
        SetTextBoxText("TERMINADO...")
        Terminados = Terminados + 1
    End Sub
 
    Private Delegate Sub enableTextboxInvoker(ByVal tb As TextBox)
    Private Sub enableTextbox(ByVal tb As TextBox)
        If tb.InvokeRequired Then
            tb.Invoke(New enableTextboxInvoker(AddressOf enableTextbox), tb)
        Else
            tb.Enabled = True
        End If
    End Sub
 
    Private Delegate Sub SetTextBoxTextInvoker(ByVal text As String)
    Private Sub SetTextBoxText(ByVal text As String)
        If tbPlaca1.InvokeRequired Then
            tbPlaca1.Invoke(New SetTextBoxTextInvoker(AddressOf SetTextBoxText), _
                               text)
        Else
            tbPlaca1.Text = text
        End If
    End Sub
 
End Class

[jmcilhinney]

Follow the CodeBank link in my signature and check out my post on Accessing Controls From Worker Threads for a more detailed explanation of the principle Paul has used.

[helderjsd]

Dear .Paul.

It works perfectly

Thank you

Post Resolved