VS 2008 - Multithread - Manipulate Something That Is In A Different Thread - Invoked Procedure ?
Jul 7, 2009
I'm trying to manipulate something that is in a different thread, and I know I need to do something by the way of Invoked procedure, but I'm unclear on how. I looked up some examples here on the forums and tried to follow the basic template, but I continue to have the same problem. how to use invoke correctly.
Private Sub getMessage()
For Me.infiniteCounter = 1 To 2
'Try
[CODE]...........................
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Jun 15, 2009
How do you pass multiple parameters to a Sub which has to be invoked?Again, I've only been coding for about 3 days so please speak as if your trying to teach a child to tie his shoe.
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Jan 21, 2010
I have a thread executing the following:
vb
Do UpdateVis()
System.Threading.Thread.Sleep(Interval)
Loop
UpdateVis is as follows:
[Code]...
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May 27, 2009
I am trying to successfully multithread a piece of software I have been working on. I have an array of threads 'gen' already working, calling to a method taking a single integer as a parameter (done via typecasting).Now in this thread, when the function gets processed (for each thread a roughly 500 iteration while loop) the index seems to be getting mixed up. As far as I can tell, my threads are messing with eachother and warping values. Now this is happening in locally declared variables inside this function, not global variables.It may be useful to know that I am using a WebRequest via a call to another method. Don't know if that makes a difference or not.
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Aug 16, 2009
I currently have a browser go through the same list of sites one by one and gather updates. The problem though this takes awhile. Can a browser be multithreaded, (so it could visit several sites at a time) and if so would this take up a lot of server resources?
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Aug 31, 2009
I am doing this within a thread:For Each item As ListViewItem In lvUsers.Items and I am getting: Cross-thread operation not valid: Control 'lvUsers' accessed from a thread other than the thread it was created on.I have been able to adjust a control in a way using something like:
Public Delegate Sub ListAddNameInvoker(ByVal text As String)
Public Sub ListAddName(ByVal text As String)
If lvUsers.InvokeRequired Then
[code]....
But how do I get data from a control and pass it to another thread?
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Mar 22, 2010
Im trying to do this
[Code]...
But it will just skip to the last status (Label3.Text = "Status: Welcome")
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Jun 10, 2010
im trying to terminate a threading.thread using thread.abort the thread runs a download connection so is usually in the middle of socket.recieve or socket.send or socket.connect when aborting i just want to terminate the thread no matter what thread.abort raises an MDA excpetion. so i ticked it off in the debug exceptions menu. now it doesnt raise an exception, but the thread simply wont terminate. my program wont close unless i press top in the debugger.i cant pause downloads because i cant terminate the thread this code wasn't working?
Dim vT As Threading.Thread
For Each vT In clsDownloader.DownloadThreads
If Not vT Is Nothing Then
vT.Abort()
[code].....
as for the exception concerning threads being aborted from other threads being dangerous, how is it possible to send a message from a main thread to another thread to abort itself? as far as i know the only way to a abort one thread from another is to just kill it (because i dont know of ways for a thread to communicate with another).
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Jul 20, 2009
I recently saw some VB .NET code as follows:[code]Does assigning Nothing to service do anything? If it is a garbage collection issue, I am assuming that when "service" went out of scope the referenced object would be garbage collected and the dispose method called on the object.It seems to me that assigning this variable Nothing can't really do anything, as there could be another reference to the object around so the reference counts haev to be checked anyways.
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Dec 6, 2011
I have a project in which checkedListBox is invoked by web reference .. I have put the groupbox with other controls shown in picture but when i get the files in checkedListBox and click on download I get the error shown in picture below another how to get this top bar in checkedlistbox..
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Oct 7, 2010
I'm firing a thread to unzip a file. I need some way of indicating to the parent that the unzip thread has ended. I've tried raise event in the unzip thread to a sub in the parent but this runs the sub from the unzip thread. With ApartmentState set to STA, so that I could use a save dialog, this was OK until I displayed a messagebox which was hidden behind the main UI(and whatever I did I could not get it to the front).
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Jun 30, 2011
Writing a custom validator for a dropdownlist that is using autopostback. Seems to ignore the validation altogether. Why is it ignored and is there an easy fix? Note I did not use ControlToValidate
asp.net:
<asp:UpdatePanel ID="updatePanel" runat="server" UpdateMode="Conditional" Visible="true" RenderMode="Inline">
<ContentTemplate>
<asp:DropDownList ID="ddlCommandAssign" runat="server" AutoPostBack="true">
</asp:DropDownList>
[code]....
For debugging purposes, I want it to fail every time.It doesn't seem to be executing the behind code at all. For debugging, I added the line response.redirect("dummy.html") ... which never gets called, which also indicates (I think) that the validator never gets called.
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Nov 10, 2011
i need some function like adodb.recordset on vb6.0 on vb.net but seem i cant manipulate it like recordset because i want to manipulate in retrieving,inserting and updating my record on just only how call on the database im using mysql database..
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Sep 26, 2006
There is something strange going on in my VB 2005 program that I don't understand.. I have a form that has several tab pages. Each page has one or more DataGridView controls. When a user selects an item on one DataGridView , I want to deselect anything currently selected on any other DataGridView on that tab page. The only thing that should then be selected is the item I clicked on in the current DataGridView .
I created the following code (note there is a CellContentClick handler for each DataGridView control and there are DeselectAll... and RefreshAll... subroutines for each tab page).
It's fairly straightforward. But notice where I placed the XXX NOTE comment below. If I place a breakpoint there, run the program and click on various cells in various grids, and then click on the specified grid cell, I can create situations where the breakpoint is never reached! Thus, I don't turn off the selection in other grids.
How can this be? Is there some setting for DataGridView controls that I've inadvertently set incorrectly (without my listing them all here)? Or is there some bug in VB I'm unaware of? The "DeselectAll" subroutine merely iterates over all DataGridView controls in the current tab page (except for the current DataGridView) and calls ClearSelection on each such grid. RefreshAll calls Refresh on every DataGridView on the current tab page.
[Code]...
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Oct 16, 2010
I'm making a little program in where i'm trying to invoke a method from a class dynamically with so called Reflection.
The class I'm trying to call is called ContactList and i try to invoke the property in this class called count. The assembly itself is called Contact.Exe
Now I have the following code where I make an instance of the ContactList class in the Contact.exe assembly:
[code]...
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Feb 23, 2012
I have a form in Visual Basic that is adding a row of data to an Access Database.What will happen (or rather what I would like to happen) is that when the form is created, a row will be added to said database. Once that row is added, I want to have another form open (called NewWindowA) which will pull information on that database that is related to the ID of the row that was created from the first form.I know that in NewWindowA I need to have the form load the values on Load. But my question is: How do you pass a value to a new window that's invoked by some action?
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Aug 13, 2010
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"
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()
[code]....
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".
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Nov 3, 2011
This is the error message I am getting:
"Cross-thread operation not valid: Control 'Panel1' accessed from a thread other than the thread it was created on." The reason I am getting this error is because I am opening up a new form and then calling these three things:
Panel1.Show()
Label1.Show()
Label2.Show()
why I get this error message because it doesn't occur normally if I open Form2 after closing Form1, it only occurs when I open Form2 after closing Form4.
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Jul 21, 2009
I have done a program using vb2005 to display reading from my microcontroller bs2 board but have encountered some problems. My code are as follows.
Dim Stop_Rx As Boolean
Private Sub btnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRead.Click
SerialPort1.Open()
[code]....
I've encounter an error which is, (Cross-thread operation not valid: Control 'txt1' accessed from a thread other than the thread it was created on.)
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Jun 21, 2012
When my client try to connect to server I'm getting this error : Cross-thread operation not valid: Control 'l_users' accessed from a thread other than the thread it was created on.
Private Sub _socketManager_onConnectionAccept(ByVal SocketID As String) Handles _socketManager.onConnectionAccept
l_Users.Items.Add(SocketID)
End Sub
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Feb 17, 2012
Would anyone be able to help me here please. I'm fairly new to VB.net and threading so im just trying to figure out what is happening.When I debug this I am getting the error thread operation not valid: Control 'ProgressBar1' accessed from a thread other than the thread it was created on.
I'm a little lost as to why the error is occuring or how to fix it. I've had to put the progress bar in a separate thread otherwise the GUI crashes
[Code]...
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Sep 2, 2010
My understanding is that thread.join will suspend the execution of code on the calling thread until the spawned thread finishes or is aborted...
With that in mind, I tried this:
For i = 1 to 50
threads = New Thread(AddressOf test)
threads.IsBackground = True
threads.SetApartmentState(ApartmentState.STA)
[CODE]...
However, the rest of the code runs when the loop finishes, not waiting for all the spawned threads to finish. Since the rest of the code needs the threads to finish (otherwise the rest will error).
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Jun 6, 2010
I have written an application that loads a form - frmCad as well as AutoCad. It does this via a class which detects when AutoCad quits.
Friend Class CadApp Private WithEvents AppObject As AcadApplication... Private Sub AppObject_BeginQuit(ByRef Cancel As Boolean) Handles AppObject.BeginQuit RaiseEvent Quit() End SubEnd Class
My main class loads frmCad as well as CadApp.
Public Class Cad Private WithEvents frmCad As CadForm Private WithEvents app As CadApp... Public Sub ShowForm() If frmCad Is Nothing Then frmCad = New CadForm frmCad.Visible = True End Sub... Private Sub app_Quit() Handles app.Quit frmCad.Dispose() frmCad = Nothing .... End Sub
When I debug the program, it stops at frmCad.Dispose()The program continues to execute, but all the code after it fails to work.Looking more carefully I get an error message which contains:-Cross-thread operation not valid: Control 'Autocad' accessed from a thread other than the thread it was created on.
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Feb 9, 2011
My error:Cross-thread operation not valid: Control 'label2' accessed from a thread other than the thread it was created on. I want to be able to give my Public RunBot() sub access to edit Labels, buttons, etc without an error.
[Code]...
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Apr 1, 2010
I'm getting the 'System.InvalidOperationException' error on acccessing a thread from other than where it was created. My code is:
'Required by the Windows Form Designer
Public components As System.ComponentModel.IContainer ' changed from private
[code]....
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Jun 6, 2009
My problem is Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on.
System.InvalidOperationException was unhandled
Message="Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on."
Source="System.Windows.Forms"
StackTrace:
[Code]...
i used it and it works fine then. but as it is mentioned its not a good practice to use it. So what should i do? is it ok if i use this as i am not able to use correct practice. Mine application is not for enterprise purpose. its just my class project, and it works fine even if i put application working in background. System works ok. I dont know how to correct this error.As i dont have that much knowlege of threads.
So please guide me how to fix this in correct way otherwise i am force to go for bad programming practice
Please refer to Windows Mobile Developer Center > Smart Device Development Forums > Windows Mobile Development > Appendtext not working for all my code details
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Feb 8, 2011
http:[url].... contains a Visual Studio 2010 Solution with a Form and a User Control.
Question. Why isn't OnMouseMove (at top below Constructor) being called with every movement of the mouse across the UserControl's grid?My intention is to have a reticle (crosshairs) replace (override) the existing mouse cursor and show a reticle with x and y coordinates?I have another form upon which a User Control with similar functionality is working perfectly.
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Aug 4, 2009
Cross-thread operation not valid: Control 'lv1' accessed from a thread other than the thread it was created on.
Dim lvi As ListViewItem
For Each lvi In lv1.Items
[code]....
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Feb 23, 2011
I'm making a type of download manager which downloads parts of a file using HTTPREQUEST.addrange. The parts download without a problem and currently I use 5 instances of the same class to download the parts simultaneously each one downloading a different section of the file. Now my problem is that I don't want to save each part as a file then merge them later, I want to use a singular filestream and append everything asynchronously. In the code below I attempted to use the seek method but it feels like it changes the seek for all of the other parts as well.
[Code]...
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Nov 17, 2011
how do I multithread using timers. For instance 3 picture boxes that change ever 3 seconds?
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