I am having trouble accessing the main thread (my form) when calling thread is running in a class (or module). I have no problem to manipulate a data (in a thread) from a form, the textbox can be updated using delegate and invokerequired but it doesn't seem as easy when the thread that processes a variable is handled by a thread that is running in a class.
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im still stuck and i really to get past this and move onto the rest of my program. I'm trying to update a textbox with new text from another class on another thread. I can get this to work no problem on another thread with the same class, and on the same thread in another class. but not on another thread on another class. my code looks like this, when it is run to produces no errors but does not add the test to the text box, what is wierd is i had made some changes to the program to add multiplelines to consolebox.text and then checked console.text from form2 and it produces the values i added but those arent reflected inside in the consolebox for some reason.
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I want to start a job in a new thread or using backgroundworker to do it but havent done that before and asking you wich way I should do it. My program has a datagridview with a list of files, one file per row. I want the user to be able to select a row and then press "Start download" to start a background job of the download. I want to get events back of the progress of the download.
I have a class clsDownload that handles everything and raises events back but how do I implement the backgroundworking?Should I use the System.ComponentModel.BackgroundWorker inside of the class or create some wrapper that handles this or use some other threading stuff?
Edit: I dont understand how to implement my download in the backgroundworker, any small example would be very nice. The example on msdn didnt get me far.I have a download class that has a StartDownload-function. Should I use the backgroundworker IN the class or in the caller? "feeling stupid"
I have a VB.NET 2010 app that uses a backgroundworker to process MS Word docs. All of the code does what it is supposed to do, except when my code calls ReportProgress(). The UI cannot process the ProgressChanged event fast enough before the values in the class that are passed are changed. I know this because I inserted a System.Threading.Thread.Sleep(100) line after each ReportProgress() call which allows time for the UI to make the updates properly. I guess I am looking for a better solution thanThread.Sleep(100) since this adds to the amount of time it takes to process all of the files. Here are some snippets of code that I am using:
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I am instantiating a form object in my code behind the dataset just to access some form level variables and to occasionally set a label in the navigator bar. Recently in the b2 Team version of VS2010 there are some strange errors thrown in the immediate window and then I'm tossed out of debug mode and back into the IDE. This code has been operating for some time in this project without this behavior. A team member has just reproduced the behavior in his development machine also.The error that starts the shutdown of the debug instance is this: Control accessed from a thread other than the thread it was created on.
View 4 RepliesThe code below works fine when I put it in form1.vb and change "form1" to "me" but I can't seem go get it to work from my class.
VB
Imports System.Threading
Public Class Class1
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I was a vb6 user, done a few projects only with forums Now i am moving to vb.net(vb2010) and i have some trouble.Lets say we have a form(form1), a module(mod1) and a textbox on the form1.
i want to start a Sub (DoWork) in the module but in a new thread.
Dim Thread1 As System.Threading.Thread
Thread1 = New Threading.Thread(AddressOf mod1.DoWork)
Thread1.Start()
The DoWork sub does some stuff and when it's finished i want to change the text of a textbox1 in the main form and start another sub (DoWork2) on the main form under the main thread not the one DoWork is running under.
Plese do not refer me to another post that mighe give me a part answer, try to explain to me what i have to do and why.
Updating the TextBox from a Thread that calls a function within a Class does not work. I'm trying to get this to work in a DLL (but I tried without as well). The DLL is accepting an Object as an argument[code]....
View 1 RepliesBasic function - enter 5-10 urls. Download all web pages using multi threads and then process it. Then in the end, the text from all threads should end up in a richtextbox. It can't be done using any of my googly searches so i thought about asking this :
how would you update text in a richtextbox from a different thread?
I am being able to download and process web pages. But can't add it to richtextbox.
I have a problem with this program
Form1.vb
Imports System.ComponentModel<br/><br/>Public Class Form1
Public Delegate Sub updatePB(ByVal value As Integer)
Private bgworker As BackgroundWorker = New BackgroundWorker
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I've been searching around for ages now but can't seem to find what I'm looking for, anyway came accross this wonderful place so thought ay I'm creating a rewards system for school where pupil earn points for good behavior which they can then use to purchase things like a packet of pens. (They can also have points deducted for bad behavior)
View 2 RepliesI created a new thread to run with a loop to update a textbox (this is just a demo, in reality this thing would go out to a db every x minutes to request an update). I did this on a timer, but i wanted to try to do it on a different thread.. anyways, this is what I have: (one form, one textbox, and this code...)[code]I'm getting a warning through (the "Thread.CurrentThread.Sleep(2000) part is underlined) which states:"Access of Shared Member, Constent Member, enum Member, or Nested Type through an instance; qualifying expression will not be evaluated".
View 5 RepliesI have a textbox which will accept a user input for a email address or phone number.I want to using a new thread do a search for various results and populate a listbox.I know i need to do this in another thread so my main form will still operate but how can I do this? I've never used threads before and I know it's tricky to get the values from a textbox and also update a list box on another thread.
View 16 RepliesI've been programming in vb.NET for a whileAnd to be honest, its turning out to be a real pain.Here is the
Form1.vb: Imports System.Threading
Public Class Form1
Dim trd As Thread[code].....
So, I have a form (form1) with a label on, this label simply reports the status of the thread.The thread begins the Class1.Main() sub, and I have a delegate setup to change the text propoerty of the label.Now,I know the label is created on the UI thread,so I assumed the delegate would work. However,it seems that it updates the .text property, but doesnt redraw the control when .Update() is called .What am I doing wrong?I have found lots of examples of delegates, but all run from within the same class. I want to use threads too, not a backgroundworker! This code is a "simplified" version of a project I am on, which is encountering the same problems
I want to change the value of text box from a thread of another class[code]...
View 3 RepliesI have on timer thread that needs to pass every time a different data to another running thread to make the calculations.
View 5 Repliesi have a query iam able to add items in listbox from form 2 to form1 from windows application in vb.net
but iam unable to add items in listbox from form 2 to form1?
I have an application that performs database queries using "Imports System.Data.SqlClient". I want to display an animated GIF on the taskbar which spins while the query is running. However, during a query the application simply hangs and does not update the GUI until the query has finished, at which point the spinning icon is set to invisible anyway. Is there any way to force the GUI to update while the query runs?
View 2 Repliesim trying to access a richtextbox from another class and thread then the ui and i cant seem to get it working. I currently have the sub thats handling the the work inside of a public class and its a sharedsub, im going to be calling it from several different classes and threads but again i cant seem to get it working. the code looks like this. Public Class SharedSubs
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i would be calling sub using SharedSubs.Console("stringstring") when this is called from the ui thread it works fine but when its called from anyother thread or class its does nothing,ive confirmed it going thru this code but its not displaying anything in the textbox and its not thru an exception due to delegates either which i figured it would.
I am trying to update a textbox before the program has finished running. If you have a counter (z +=1) how to you get it to display each number to display before the program finishes running?
View 1 Repliesi have a query iam able to add items in listbox from form 2 to form1 from windows application in vb.net but iam unable to add items in listbox from form 2 to form1
View 3 RepliesThis is my first post on this forum, so please excuse me if I'm posting wrong. Anyway, I've been having an issue that I've never seen before and is driving me nut, I have a windows form on which I have placed many textboxes that display information from a MS SQL database. The user can then change these values and hit a "save" button which writes the changes to the database. I also have certain textboxes that with the "on leave" event (after a user enters a possible new value) trigger a method that recalculates some of the other fields based on the new information. Hopefully that all makes sense.
So the problem is, when I run through this "recalc" method the first time around, it doesn't update those textboxes that it's supposed to. However, when I put a breakpoint in and debug through it, the debugger shows it putting in the correct values into the textboxes. It's just as soon as the method is done, it puts them back to blank, or whatever they were before
'Rebind stuff here
lblCabinets.Text = curMfg.ToString("c")
txtCabinets.Text = curMfg.ToString("c")
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I am wondering how do I update a Progress Bar that resides in Form1 (for example) from a newly created class called from the Button in Form1. I have read several tutorial about backgroundworker. Most of the googled tutorials have their "long process code" in the do_work event. I have tried them and got it working from within the form itself.
However, there are 2 parts (long process) in which I wish to incorporate the updating of the progress bar; First one being a long sub routine that is in the main form (Form1). The second one is another long processing function that resides in a class. It is the second one that is giving the problem as I have no idea how to call the backgroundworker.reportProgress() to update the UI.
Here is the sample flowchart that I have created for the second long processing function:
I wish to insert a new instruction that says "Update the Progress bar that is in Form1" after the current instruction "Store the member into a collection".
I have a function called textupdate that updates text1.text value. when i call this function in Form1_Load, text1 is updated successfully. However, when i call this function in Private Shared Sub function2, no update is done. I am a newbie in vb.net programming and it may be a silly question but I could not solve it
View 1 RepliesA BackgroundWorker thread can pass data to the primary thread. It does it via the RunWorkerCompleted and ProgressChanged events, which I believe run in the primary thread. I would like to encapsulate the BackgroundWorker control in a class so that I can instantiate it more than once. But I don't know how the BGW can then communicate with the primary thread. If the BGW control is within a class, it does not have access to the properties outside the class. In that case, how can the BGW pass data to the thread that instantiated it?
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I have a 3 questions that I would like to ask....
I have made a kiosk type software (for my 7 year old daughter so she can only do what I want her to do on one of our computers)
1. I have a toolstripcombobox that will be where she puts in the url's. I need information on keeping the history of where she goes? So when she clicks the arrow to the right it lists all the sites she has been to.
2. Right now, the webbrowser navigates to where the url is (www. vbdotnetforums.com), but when you click a link it dosn't update the textbox with the new url [URL]. It just stays at the first url.... Anyone know how to fix this?
3. Any help being able to add tabs and load the tab with the url like internet explorer?
I have a program that runs for some time and I would like to update the user on its progress. The rest of the GUI is updated using Delegates and Invokes and such (Java is Soooo much cleaner in this regard - everything is thread safe!!), but there is no invoke method for the progress bar. How can I use a delegate to update the progress bar when there is no invoke to invoke!!
View 1 RepliesI am using vb.net 2005In my form load procedure I am starting a background thread.The thread is declared as public.
Public
threadMonitorWMI As System.Threading.Thread
And started in form_load
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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.
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My routine to check for updates is run as a separate process. Exiting the application is required to update, so a dialog asks the user, when an update is found, if they want to exit now. f they do, the code (from the update thread) calls Application.Exit().However, if the FormClosed event of any form that needs to be closed needs to access its controls, an invalid cross-thread operation is detected (which sounds pretty logical).
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