Create An App With A Backgroundworker To Enable Canceling A Loop?
Feb 22, 2009
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?
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May 13, 2010
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.
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Aug 17, 2009
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.
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May 29, 2012
I have this little application that runs a SQL query works great, now I want to have a Start Button run the and display results then System.Threading.Thread.Sleep(300 * 1000) for 5 min then run again and display results and loop till I buttonstop_click. unsure if the sleep is the best method.
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Dec 23, 2011
If I want to enable a bunch of textboxes and I have the names of the textboxes stored in a string array, how can I use a foreach loop to enable each element?I've tried the following, but it doesn't work.
Dim strElements = New String() {"chkFirstname", "chkLastname", "chkCompanyname", "chkFullname", "chkContactTitle", "chkEmail", "chkAddress", "chkCity", "chkState", "chkZipcode", "chkHomePhone", "chkWorkPhone", "chkFaxPhone"}
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May 9, 2011
I'm completely new to working with more than one thread at a time but I've been reading up on backgroundworker quite a bit today. I get the general idea and think I could use it ok if it weren't for the fact I have a loop in a loop and I don't think they could be run inside a single thread together
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Jul 5, 2011
I have a backgroundworker that is downloading data from different webpages and process them to a datagridview.I get the Cross-thread operation not valid error on the first For loop.
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
dim i as integer
tot = (numPostnrTo.Value - numPostnrFrom.Value) / 10
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Oct 17, 2008
Working on a project that tests up to 16 PC boards. The test routines are on a a backgroundworker thread. I want each PC board to perform the test routine on its own thread, so I would need up to 16 backgroundworkers.How do I go by doing this? Do I put 16 Backgroundworkers on the form? I tried to do it programmatically but I can't declare an array of backgroundworkers because withevents variables can't be typed as arrays. I guess I just need a kick in the right direction.
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Apr 4, 2009
Dim WithEvents backgroundWorker1 As New BackgroundWorker
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I want to use a backgroundworker to create part of an interface. In particular i want to open a page and as soon as the page is open a new thread should start to create a stack panel with many elements inside( lets say labels) when the thread has finished to do its work this stack panel should be added open page Is this possible?
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Jun 16, 2011
I have a VB.net project which uses a background worker to do some stuff.
Now I want to expand the project to be able to do multiple stuff :)
A user can enter an URL in a textbox and when the user click on the parse button the program creates a new tabcontrol a outputs some data.
I use a hardcoded background worker for this.
But now I want to run multiple background workers to do this stuff so I can't rely on hard coding the background worker(s).
Is it possible to create background workers dynamically.
how to set this up since I think I need to set up the different methods and variables like:
Private bw As BackgroundWorker = New BackgroundWorker
bw.WorkerReportsProgress = True
bw.WorkerSupportsCancellation = True
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I think I need to declare the background workers in some sort of array like variable (list / dictionary)??? Other then that I have no idea how to tackle this.
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Jun 11, 2012
I'm trying to create a small program that will import a list of IP addresses from a text file into a list box and then run a continuous ping on each address (from the list box) and display the results in a label using backgroundworker. The idea is to have a small visual display of the status of network devices.When I try to use a list item I get cross-thread errors.[code]
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May 31, 2010
So I made a simple patform game where the player has to jump quickly while the platforms move to the bottom of the screen, as to not touch the bottom of the screen. But, I need to know how to create a loop to loop the locations of the platform. This means that after twenty or so platforms, the same platforms come up again, so that the player will have an "endless" game. I've declared all the platform's locations relative to the location of the first repeating platform:
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Sep 18, 2009
I have a client app written in VB (Visual Studio 2008) + VS 2008 SP1. I can see the option "Create desktop shortcut" under --- Publish > Option > Manifest but it is disabled.What do I need to do to enable it so I can have it checked before publishing it?
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Dec 14, 2009
in my button click event i ececure
If BackgroundWorker4.IsBusy Then
BackgroundWorker1.CancelAsync()
End If[code]....
after proceess completed if press the button again.i got the following error msg
This BackgroundWorker is currently busy and cannot run multiple tasks concurrently.
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Dec 10, 2009
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.
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Mar 13, 2008
I want my application to be able to communicate 2-way between the application on another computer and the host server which will be running on my computer.I want to use the BackgroundWorker built into vb to create a thing to make it listen for incoming messages, and also send out messages to the client.The client needs to listen and receive, same as the server, because both need to communicate with one another.I do not know how I can make it do either sending nor receiving.I would be using two different background workers to keep the code seperated and organized so that I will understand what code is for what.
I want the code to say that if i receive the message "Apple" without the "" and cap sensitive, then it will change Label1.Text = "That worked, word received Apple" or something similar to that. ( This is because I am ignorant and I want it to interpret the text sent through to figure out what the application is supposed to do, and last time I couldn't figure out how to make it do something when a certain text was received.
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Mar 4, 2010
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
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Nov 21, 2010
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.
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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?
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Sep 17, 2010
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.
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Jun 19, 2009
I want to allow the user to enable or disable a textbox by clicking either a button (enable) or the reverse. (disable) if the user clicks the enable button the textbox should receive the focus.
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Aug 14, 2009
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?
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Jul 18, 2010
Right basically if a checkbox in my application is checked "Close to system tray" then my form will cancel close and send to tray instead
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Oct 12, 2009
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
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Jul 21, 2010
Dim count As Integer
For count = 1 To 10 Step 1
Dim But+count As New Button
myButton+count.Width = 100*count
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Dim But+count As New Button => How to make it work
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May 6, 2011
seriously struggling with this one bit of a program im creating. Im trying to simulate a moving queue, using a number of pictureboxes (controlled by Timers). Once a picturebox vanishes, another appears in front of it to symbolise movement throughout the queue.Anway... Im struggling with LOOPS! I cant seem to make the funtions repeat and I need this urgent due to a deadline in 16 hours time Background Info: The form will run for 60 seconds, after which anotehr form will loads (MorrisonsQueueSummary).Here is the syntax so far:vb.net
Public Class morrisons
Private Sub FormTimer_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MainTimer.Tick
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Sep 14, 2009
Is it possible to create a loop using a string I am writing a program and I need it to output 3 letters ahead of the letter you input for instance if you input a then it outputs d and if you input u it outputs x, and also the same with capital letters A then D U then X and so on. I have writted the program the only problem is that when I input X I want it to output A but it outputs [ instead I need to create a loop where when I input X it starts the alphabet over again, and I need to know if it possible and if so how will I go about doing so.
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Mar 14, 2011
Makes the following statement about the code below:
**"The computer evaluates the loop condition in the Do...Loop statment to determine whether the loop instructions should be processed. In this case, the inputsales <> String.Empty condition compares the contenst of the input sales variable to the String.Empty value. As you know the String.Empty value represents a zero length, or empty, string if the inputsales variable is empty, the loop condition evaluates to True and the computer process the loop instructions. *If on the other hand the inputsales variable is not empty, the loop condition evaluates to false and the computer skips over the loop instructions.
Based on the code I think it is the opposite: ...that while the inputsales value is not empty it should evaluate to true and process the loop and if it is empty it should evaluate to false and skip the loop?
See below.
Option Explicit On
Option Strict On
Imports System.Globalization
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Apr 2, 2012
i'm in the need to start a backgroundworker inside another one.Now...The first one BGW starts a for cycle, and inside this one there is the second BGW that has to upload an image to a server.The trouble is that, the progress event and the complete event of the internal BGW are never called.
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Feb 23, 2011
I want to loop through my datatable column called SDESCR and created a string that looks like this.
Dim labels As String() = {"North", "South", "East", "West", "Up", "Down"}
this is what i am trying and it is not working
Dim labels As String()
For Each row As DataRow In tablegraph.Rows
labels = labels " ' " + row.Item("SDESCR") + " ',"
Next row
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Jul 12, 2011
What is the best way to create a delay between interations in a loop, somewhere around 1 to 5 seconds?Example:
do
'Do something
Delay number of seconds?????? How do I do this
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