When using the backgroundworker, I know that the DoWork event is not suppposed to support cross thread operations for controls. I have a public integer variable declared on a different form that I need to test in the DoWork event.The backgroundworker seems to not be able to check what the variable is, as the test never enters inside the if/end if check. If I copy the code exactly to a different sub (IE, not a background worker, a normal sub) and call that sub instead of starting a background worker, the if/end if always gets entered.I'm confused as to why it won't raise a cross thread exception, but won't test the variable that makes the check true (as it does in the test sub).I added in a try/catch block and that doesn't catch any exception either. I tried a timer and started the new sub with that timer, but that still completely locked up the app...
I have a form with Check Boxes on it and a second form that holds functions and a Backgroundworker.When a button is pressed on the first form, the second form loads and then runs the functions that relate to the appropriate Check Boxes.Doing it this way causes the second form to become inaccessible. I decided to run my code in the Backgroundworker's DoWork event and then call the RunWorkerAsync method in my form's Activated event. Before using the Backgroundworker, everything worked fine and now it doesn't.I assume the issue is with the Backgroundworker not being able to access controls on another thread.In debug mode,it automatically throws an exception, but doesn't error out when using the Release version, making me assume it's a legal call. But, if it's a legal call, then why can't I access the controls?
I have some variables that are distinct by numbers, like in1, in2...If I have for loop, how would I access those variables, using the counter, and attaching it to the variable?I believe in JAVA, you could just use in+ct... where ct is the counter to access the variable.also how could you make a new variable in the for loop?Initially I had variables declare outside of the for loop. The problem was how to access those variables using the for loop.
var_nm1 = in1.Text var_nm2 = in2.Text var_nm3 = in3.Text Dim nmList(2) As Integer
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This is object oriented programming, and I made the textboxes in1, in2, and in3 using the GUI editor. that was so easy.
I am using this example I found to learn how to load class files and access variables through them. This is in a file called Class1.vb in the App_Code folder (this is not an app project):
Imports Microsoft.VisualBasic Public Class my_class Public Shared Sub my_sub()
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How could I access the vartest variable without using a session, since if this is accessed by multiple functions at the same time the variable can be overwritten I assume. Is it possible to go the other way, where a variable is sent to a class file?
I have created a public shared subroutine in a class file in asp.net 2 (vb.net) web site app_folder.The subroutine retrives some values from a sql database via an sql query and assigns the datareader field values to several variables The problem is I can't seem to assign the variables from the subroutine to the variables and textbox controls in the asp.net page I am calling the subroutine from. The textbox text value just appear blank.By the way, if I response.write the variables in the subroutine they appear populated by the sql data reader.
I am currently working on a project of "interpreting" C# into VB. The project involves adding images to a database, retrieving images from the database and presenting them in thumbnails. Right now I have the following Public Class with the Variable that needs to be assigned:
I'm not sure of the syntax necessary to access a class's attributes inside of a Dictionary declaration.
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So if I want to test it and use MsgBox() how do I trickle down to pull, say, name in food > cheese1 > info > attributes2 > name?
EDIT:I just realized that Array in info needs to be a Dictionary for an associative array, so please ignore that error and just assume it is a Dictionary for this question's sake.
I have a Public Sub I am using to enumerate running processes and then display them in a ListView.I want to be able to update the list automatically each second. I've thought of doing this in two different ways, but the method that I want to use is checking if the process has exited or not.
When reading up on the Process Properties, I ran into .HasExited and .Refresh.I thought that I could use a timer and have it tick at 1 second intervals. I would then check, each second, if the Process has exited. If it has, remove it from the list.The problem with this, is that I don't want to put the sub in the timer because it would just constantly flicker the control. I need to figure out a way to access the variables inside of the Sub while inside of the Timer's .Tick event.The other issue is being able to add processes that aren't there. Which I can within another sub. I was thinking I could create a sub that grabbed the Processes by ID, compare them to the list, and them add them if they aren't there. If I did this, I could also remove Processes by ID that aren't in the list.
I have an array of variables called VolumeArray(12) which is declared as publlic shared in the main form1.I have a second form2 which allows the user to input various values. When this form2 is closed, I need the data the user has entered to update the values for VolumeArray(12) within Form1.
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.
Last year (2010) I came across a FANTASTIC command that allowed me to take a string of variables with a common delimiter and break it all back out into separate variables (possibly an array) with one statement.
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As long as the delimiter was a unique specifiable character, this one-statement command could break it out into elements. my memory and point me in the right direction.
I have code, shown below, that works all except for 1 thing: The variables being passed byRef get passed, but once modified in the else section of the "if me.invokerequired" code of RecordData, the variables are never updated in the calling function. To reiterate, the calling function does not receive the updated data that is in the variables custid and amt.When debugging, I see the data change in the else section of "if me.invokerequired", but once it returns from the callback the data is missing.[code]
I define some global variables of a class as follows:
Private Class MyClass Private var1 as Decimal Private list1 as List(Of string)[code].....
But I found that after this form is closed, all above variables, var1, list1, list2 still exist in memory. I thought they should be collected by gc since the form is already disposed as I confirmed.
Add: I have monitored half an hour after the form is closed. But these variables are not collected by gc. I have an automatic update procedure on the form which uses above variables.Since the above variables still hold values, the automatic update procedure is always called which causes exception. (One quick fix is to check if form.isDisposed in update procedure. But I do not think this is elegeant. Besides, these variables occupy memory.)
Does the memory used in declaring variables are reclaimed by the OS when these variables go out of scope?Does the memory used be released by setting thier value to nothing? if not, then how can I force the garbage collector to run or excecute at a certain/desired time..How about in Windows Forms..How can we make sure that the memory used in initializing and showing forms be released if those forms were closed?
Question 1: What is the difference between "Background Worker" and "Worker Pool" as indicated within the MSDN samples provided.
Question 2: I noticed while using, AddressOf _Function_, variables cannot be passed; what would be an efficient solution to this?
Question 3: While using multithreading is it required to invoke before setting variables, or only form properties?
Question 4: While using System.Net.Sockets is it safe/efficient to use Application.DoEvents while waiting for new data; or would be using a Do While loop be fine without DoEvents since the action would be multithreaded? Note: there can be up to 2000-3000 sockets in use at a time.
I'm new in .NET programming.I have a class Form1 that includes Button1_Click event.Button1_Click creates a multiple Text Boxies at run time)Here is the class:
Public Class Form1 Dim shiftDown As Integer Dim counter As Integer
Basically in visual basic 6 I could access word tables in existing templates with the code owordactivedoc.tables(1).select() where owordactivedoc refers to the active word document and tables(1) refers to the first table in the template.Trying the same code in VB 2003 just leads to errors. Secondly how do I access bookmarks or alternatively word variables.Furthermore how do one deploy web.services. For example the current program I am building is for another computer. Simply copying the web service to Inetpubwwwroot dont work because it is not picked up by the Internet Information Services program. I have to create the web service in vb2003 on the other computer change msconfig manually. Copy and paste the existing service vb file in the created folder replacing the empty vb file.
good example on backgroundworker control in vb.net for doing some process in background for ex a reading a doc file in textbox by using backgroundworker in vb.net?
I've got a bit of a problem, I'm using a backgroundworker to do a lot of processing and it adds items to a listview with: AddListItem(ListView1, listItem)
Here is the delegate code to send the command to the listview outside of the thread:
Delegate Sub AddListItem_Delegate(ByVal [ListView] As ListView, ByVal [text] As Object) Private Sub AddListItem(ByVal [ListView] As ListView, ByVal [text] As ListViewItem)
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The problem is, as you might imagine, flickering of the listview. Can anyone help me out with a solution to execute a LockWindowUpdate(Me.Handle) command in the backgroundworker? I've tried creating a new delegate but it's not working (errors, I don't understand vb.net enough).
I have limited experience in VB.net and have become stuck. I have tried to search for answers on other threads without success.I have an application that displays real time data.Queries are made to a MySQL database on another PC over the internet every 10 seconds to gather the most recent data.I have done the query within a BackgroundWorker so that the GUI is still responsive while the query is answered.What I've done works great for several hours or maybe for a couple of days but then the DoWork task appears to hang.
The code I'm using is to run the background worker is:
vb If Not(backgroundWorker1.IsBusy) Then Me.backgroundWorker1.RunWorkerAsync() End If
The backgroundWorker runs just once and there's very little code in the DoWork routine:
vb Private Sub backgroundWorker1_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles backgroundWorker1.DoWork rs = New
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Is there anyway I can set up a timeout on the maximum allowed time that the DoWork task can be active for? And if so how would I then go on to stop the backgroundWorker?I understand that CancelAsync isn't going to help as my DoWork task is not repeating as it runs once only, then stops and 10 secs later I run it again.
I'm trying to add a backgroundWorker to my application, but I can't find it.I tried looking in the toolbox, but didn't find it. I looked in the Choose items dialog box and it is checked. Tried unchecking and checking it again, no difference.
I tried using Dim worker As System.ComponentModel.BackgroundWorker but get an error:
Type 'System.ComponentModel.BackgroundWorker' is not defined.Is there any way to add it to my program?
I used sample from jmcilhinney at Link to create background proces and it works like a charm. But. In my menu i have two (2) different toolstrip buttons which i need to run the same BackgroundWorker1_DoWork method, but different ackgroundWorker1_RunWorkerCompleted methods. Is that doable?
1. In BackgroundWorker1_DoWork method i use some time-consuming operation which at end sets two global variables.
2. In BackgroundWorker1_RunWorkerCompleted method I use some Select case statment based on that two global variables that are not the same for ToolstripButton1 and ToolstripButton2.
Vb.net Private Sub FirstButtonToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles FirstButtonToolStripMenuItem.Click
