I have a few classes. One of the classes handles everything to do with updating controls (Such as adding items to a listview, etc.) and another is handling loops. I'm trying to add something to a richtextbox from another thread.[code]..
View 3 RepliesI have some controls in a .net 4.0 form - a listbox and a listview item.I also have another thread in the same class which is checking a host for output.It uses delegates to display all incoming data to a richtextbox - this works fine.If the data has a particular signature it sends it to a parser sub in another module.This module tries to update the listbox and listview items with that data after it has manipulated it.The problem is; no data is displayed and no errors are thrown.If I add a msgbox("Test") after the code, it shows the messagebox.If I add a test messagebox inside the delegate function, it shows the messagebox. If I put the same MainForm.ListBox1.Items.Add("Howdy") in a ButtonTest.Click event it adds it correctly.
View 14 RepliesIn 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".
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.
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.)
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
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.
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]...
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]....
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
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]....
Ok i have a Form with the following
Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
txtNotepad.Text = LoadFile("notes.txt")
[code].....
When i run the program i am getting the following error in this line TextBox1.Text &= "File Created: " & FullPath & vbCrLf"Cross-thread operation not valid: Control 'TextBox1' accessed from a thread other than the thread it was created on."
View 13 RepliesI need your help on the following. In debugging mode only the program is stopping to the following line "My.Forms.FormMain.HelpProviderMain.HelpNamespace = "Reports.chm"" with the following error ""An error occurred creating the form. See Exception.InnerException for details. The error is: Cross-thread operation not valid: Control 'FormSplash' accessed from a thread other than the thread it was created on.""
I noticed that when I am putting NONE in SPLASH screen option in the properties of the project, there is no problem.I am no familiar with treating that's why can you give me detail instruction how to overcome this annoying problem?
In debugging mode only the program is stopping to the following line "My.Forms.FormMain.HelpProviderMain.HelpNamespace = "Reports.chm""
with the following error ""An error occurred creating the form. See Exception.InnerException for details. The error is: Cross-thread operation not valid: Control 'FormSplash' accessed from a thread other than the thread it was created on.""I noticed that when I am putting NONE in SPLASH screen option in the properties of the project, there is no problem.
im getting this error and i cant figure it out.
Public Sub mlogin()
Invoke(chkb, New Object() {"disable"})
Invoke(d, New Object() {achidrtb, "", "="})
Invoke(d, New Object() {hiddenrtb2, "", "="})
[code]....
I'm having some trouble getting cross-thread communication/field-updating working properly in my VB.NET 2010 program. I'm trying to update a field on my main form whenever a thread that I've started throws an event. Here's a simplified version of my code:
My main form:
Public Class Main
' stuff
' Eventually, startProcessing gets called:
[Code]....
my app just freezes, and stops answering, gui freezes. Im trying to appentext to a textbox via the delegate method. What am i doing wrong?
[Code]...
I'm going to level with you -- although I heard someone say a long time ago "Never use it"! -- and it stuck with me, if I didn't have this in my form load code, my program wouldn't work.Because, to be completely honest, I could never get my head around the issue regarding the serial port and using delegates. (Haven't given up though).
Anyway, the software works absolutely fine with this statement BUT I get a several errors without it based on that "separate threads" thing (to put it in hillbilly terms). is it still "Never use it"? or am I not alone, and some of you have also used "check for illegal cross threads = false"
I'm learning VB.NET coming from a VB6 and Java background.In my app, I've got a function that validates the fields on a form. All it is doing is reading them, not updating. I've searched and see info about the backgroundWorker class, but all the examples are about updating the fields.I understand the idea of threading and how it works, but have never written code that spawned threads myself. I've always let the language handle it. It seems like a lot of work that I would have to write a sub using the backgroundWorker for every time I wanted to read or update each field. The couple of books I've got that introduce you to the language show you reading or updating the field directly.How do I know what threads are running other than writing the code like I'm used to then running through debugger to figure out what variables are on which thread?
View 2 RepliesI have Tab control and I taken Imageviewr control in 1 st tab. After I execute form I got this error:
Cross-thread operation not valid: Control 'DocImageViewer' accessed from a thread other than the thread it was created on.
adil
I get this error when i request the 'SelectedItem' property of a standard .NET ComboBox control from a BackgroundWorker control.
I know why this exception is raised, however, i thought that read-only operations to controls from different threads were safe?
I know i can turn this off using Form.CheckForIllegalCrossThreadCalls - but i want to make sure that readonly calls from non-ui threads are actually safe or not?
On a given application form, I have around 20 controls that I need to set in the main form. I have a separate thread that only needs to ready some properties from the controls on the application form It will never try to write to the form's controls.
[Code]...
I've created the example project as per this article: [URL]
But I get: "Cross-thread operation not valid: Control 'Label1' accessed from a thread other than the thread it was created on."
Is this article incorrect? I'm guessing the Label1 object needs invoking??
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."Now I know there have been some topics similar to this but they didn't really and most were confusing.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()
[code].....
I need some help to understand my options to get this working. I try to update a textbox control by a property-changed event from a class variable. I've digged around for a day and have a vague understanding that this can be solved in three ways:
1. Using some "if InvokeRequired", "Invoke" code in the handler method
2. By programming a special delegate class for this variable
3. By using a databinding directly linking the control (textbox) to the class event
Now.. Are these options correct? And would it be possible to get some help to show these three solutions in actual code (relevant to mine)? I can't seem to manage to sort all the information to a working code. Also, what are the pros and cons of the different solutions?
As my code stands now, it's obviously none of the above, as it gives a cross-thread error, as indicated.
[Code]...
I am getting this exception: Cross-thread operation not valid: Control 'TextBoxOutput' accessed from a thread other than the thread it was created on. in a VB 2008 Windows Forms application that I havent specifically made multi-threaded. I have create a sub called Out() like this:
Private Sub Out(ByVal inString As String)
Me.TextBoxOutput.Text += (Me.TextBoxOutput.Text & inString & vbNewLine)
Me.TextBoxOutput.SelectionStart = Me.TextBoxOutput.Text.Length
Me.TextBoxOutput.ScrollToCaret()
End Sub
and I call it from various events to log messages I am getting from my pbx, which I use a third party open source dll to access. The interesting thing to me is that if I run the deployed application (ie, not in the VS IDE) I do not get any exceptions, it's only from within the IDE.if I add the line: Control.CheckForIllegalCrossThreadCalls = False to the form's constructor, the exceptions stop, but a) this seems like a hacky way to get around the issue and b) the application seems to hang sometimes when I have it set this way.
I have a windows form with a progress bar and a button to start/stop the process. I am performing some action when clicked on 'Start' and updating the ProgressBar accordingly and its working fine. But when I try to click on the 'Stop' button when the process is going on, I couldn't access the Window. If I click for multiple times, I am getting (Not Responding) on the titlebar.
Then, I created a thread and run the function (which performs my task and update the ProgressBar) in it. I am getting an error that it could not access the control which is created in another thread.
I have a small problem that I am sure is due mostly to my inexperience with threading. I have used simple entirely self-contained threads before, but not to a great extent. I understand the basic laws that surround them, such as how a thread cannot access another thread's member directly, and must use delegates.
[Code]...
I am trying to call a method that started on a background thread on the UI thread calling BeginInvoke and passing in a delegate as follows:
Dispatcher.BeginInvoke(Function() UpdateApplicationDataUI())
to call this method:
Private Sub UpdateApplicationDataUI()
...
End Sub
However, I get an error in the call to BeginInvoke (the UpdateApplicationDataUI portion of the delegate is stating "Expression does not produce a value").
Me.Dispatcher.BeginInvoke(Function() New Action(AddressOf UpdateApplicationDataUI))