Help Cross-thread

[falled]

Hello I'm writting an application and I must learn threads,

This is only a test, just for fun, but I had some problems....

I've got two buttons and a textBox on the form, the first button initializes a thread, and the second stop it.

When the thread begins, starts to read a file with a number of bytes, until the end.

But I can't write to the textBox because belongs to another thread!!!

Imports System
Imports System.Threading

Public Class Form1

    'Vars
    Dim _threadArray(5) As Thread
    Dim nThreads As Integer = 0
    Dim s As New serverObject
    
    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        
    End Sub

    Private Sub ButtonX1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonX1.Click
        If (_threadArray(0).IsAlive) Then
            MsgBox(_threadArray(0).Name)
            _threadArray(0).Abort()
            _threadArray(0) = Nothing
        End If
    End Sub

    Private Sub ButtonX2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonX2.Click
        _threadArray(0) = s.initialize("D:\Prova.txt", Me)
        nThreads += 1
    End Sub

    Public Sub appendText(ByVal str As String)
        TextBox1.Text &= str
    End Sub

End Class



Public Class serverObject
    Dim path As String
    Dim fs As IO.FileStream
    Dim b(20) As Byte
    Dim temp As Text.UTF8Encoding = New Text.UTF8Encoding(True)
    Dim frm As Form1

    Public Function initialize(ByVal p As String, ByVal f As Form1) As Thread
        Dim th As New Thread(AddressOf speakToMe)
        path = p
        frm = f
        fs = IO.File.OpenRead(path)
        th.Name = "I'm the server"
        th.Start()
        Return th
    End Function

    Private Sub speakToMe()
        While (True)
            If (fs.CanRead) Then
                If fs.Read(b, 0, b.Length) > 0 Then
                    MsgBox(temp.GetString(b))

                    'Here!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
                    'Here comes the Cross-threading


                    frm.appendText(temp.GetString(b))
                Else
                    fs.Close()
                    fs = IO.File.OpenRead(path)
                End If
               
            End If
            System.Threading.Thread.Sleep(3000)
            'MsgBox("I'm alive!!!!!!!!")
        End While
    End Sub
End Class

 

[chrissie1]

So you used VS2005, because that is the version that warnes you for this thing, so you didn't read the error message and you didn't read the many examples it gives to solve this little problem.

No problem. Do it again and read it this time. Not that we don't want to help but the help function has all the answers. And google has even more.

If however you have a problem with the implementation of any of the solutions given by MS then you could come back and ask.

Christiaan Baes
Belgium

"My new site" - Me

 

[onpnt]

delegates/async calls



[sub]____________ signature below ______________
The worst mistake you'll ever make is to do something simply the way you know how while ignoring the way it should be done[/sub]

 

[chiph]

Hint:
Look up the InvokeRequired and BeginInvoke methods.

Chip H.


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