I have a program in VB2008 and I need to execute a thread from differents Subs.Each time I start the thread I want to cancel the previous.Here an example:
Private Sub TextBox_Changed(ByVal sender As System.Object, ByVal e As System.EventArgs) Dim ThreadResults As New Thread(AddressOf ShowResults) ThreadResults.Start() End Sub Private Sub ckBoxAllRecords_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Dim ThreadResults As New Thread(AddressOf ShowResults) ThreadResults.Start() End Sub
I write in a textbox, TextBox_Changed fires, thread spend 4 minutes filling a dataset I check a checkbox, ckBoxAllRecords_CheckedChanged fires, thread spend 10 seconds filling a dataset.I dont want anymore the dataset of TextBox_Changed so I want to cancel its filling.
I have a task that needs to be executed many times in a thread, so as to keep my GUI responsive. Right now I'm using the ThreadPool to accomplish the tasks, and it works perfectly. I get all the data I expect back from the threads, life's good. When those tasks are finished, I then fire off another set of threads to accomplish another set of tasks, in the same fashion. The work method of these threads uses a call to RegistryKey.OpenRemoteBaseKey, which does exactly that, opens a remote registry key. The problem is: if the user running the application does not have permission to open the remote registry the call will throw an IOException, but I expect this behaviour because the user does not have permission to do it. However, the call itself can take FOREVER.
I wrote the application initially to use delegate methods and used the WaitHandle.WaitOne() method on AutoResetEvents in a state object I passed to each delegate. I tried the WaitOne method using a timeout, which worked fine until I realized that even though the WaitOne timed out, the thread was still running. This is a problem because (from what I understand) processes are only given a certain number of ThreadPool threads and, once used, they must be finished in order to be released back to the threadpool. In my work method, I also have a variable that can be signalled when the thread should be stopped, but that (obviously) only works on code that I've written.how can I cancel a thread that's stuck on a .NET method? Is there some sort of garbage collection method I can call if I give it a handle?
I'm using a While loop that loops a certain number of cycles (1-576) based on a value entered by a user. It's activated by the user clicking a "Start" button, But I would like it to be able to be canceled using, preferably, the "Escape" key. However, when the loop is going I can't get the program to recognize any keypresses.
I've set up a background worker to search a directory for emails and if my specifi criteria (i.e. date ranges, contains a word) are fulfilled, then a list view is populated.I have this working absolutely fine - when I click search, the list view is populated as I watch - but when I press my 'Stop' button, which runs bg.CancelASync() it does not stop the process at all - results still populate in the list view as it was before.
I have a DataGridView in which I register customer orders.
The DGV has a column "PRICE", Price must be > than 100, and I control that in this way:
Private Sub DataGridView1_CellValidating(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles DataGridView1.CellValidating Dim newInteger As Integer
I'd like to start by saying that simply though searching, DreamInCode has taught me alot about VB.NET. In fact, I would imagine without DIC as a resource, I probably wouldn't have been able to move forward and learn most of what I know now, just because I got stuck on some things here and there.Anyway, I searched around for information regarding how to "capture" a minimize event in VB.NET. I am working on the GUI for an application that I would like to have minimize to the system tray. Currently, instead of accomplishing this with the minimize function, I do it on the FormClosing event like this:
Private Sub MainFrm_FormClosing(ByVal sender As System.Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles MyBase.FormClosing 'Cancel the attempt.
[code]....
That code works, and upon making the form visible again with Me.Visible = True the form is restored to its original position. However, prior to the form being hidden, the window manager draws a minimize and restore effect before eventually hiding it. Any change to the WindowState _after_ hiding the form does not appear to have any effect, so when the form is unhidden it is still minimized.is there a way to capture Minimize events, and when captured, is it possible to cancel them in a manner similar to what I did with the FormClosing event?
Really wracking my brain here and I'm sure it's something simple I'm missing. Basically I have a form with two tabs. I'm checking the controls on each tab to see if they're dirty and want to prevent a user from clicking a tab if there are changes on the current tab.
I had thought if I check the dirty variable and just set the tab index to the one that hasn't been selected I'd be fine but every time I programatically set a tab's property, it fires off a bunch of the tab's events that just produce an undesireable result such as the right control set is showing but the wrong tab is selected. Here is the code for as close as I've gotten to getting it to work.
I'm trying to create an app with a backgroundworker to enable canceling a loop, but it won't work as I hoped it would.When I debug right after the line ThreadWorker.RunWorkerAsync() the programm goes directly to Private Sub ThreadWorker_RunWorkerCompleted and skips the Private Sub ThreadWorker_DoWork part, where of course the actual code is in (I've left that code out, it's about a 100 lines and without BGW it works).Does anyone have an idea what could be wrong with it?
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".
"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.
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
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
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).
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.
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
Protected Overrides Function ProcessDialogKey(ByVal keyData As Keys) As Boolean If keyData = Keys.Enter Thenme.currentcell.value = "Hello" ' Here i want to give text "hello" to the current cell is this possible
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."
I'm creating a Client Server application which involves theServer running some scripts in clients and getting back results in an automated way. In Server, other than Main thread, i have 2 worker threads, a) one monitoring response from clients and b) the other scheduling next available job to respective client which executes that job. The issue here is ,I want these worker threads to write the status of their work in the UI(which comes under Main Thread). Also i need to write things in worker thread in a Data table and Rich Text Box in Main thread. But, I can't do so, since it has been blocked to access one thread's function or property directly from others. Is there any work around to do this?
Preface: I know this is an unusual/improper way to do this. I can do this with a "real" ShowDialog(), background worker/thread, and so on. I am trying to do specifically what I describe here, even if it is ugly. If this is impossible for X reason, I have created a fancy progress dialog for some of our long running operations. I need to have this dialog shown on a new thread while having processing continue on the calling (UI in most cases) thread.
I 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?
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.
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.
