I'm trying to add items to a listbox from another thread, but am not getting any. [Code] I've verified that inside the FOR loop, in the UpdateUI method, DOES have the correct values, they just aren't being added. What am I doing wrong here?
View 10 RepliesI've been trying to add to a listbox item from a different thread (thread 2) than the thread in which the form/listbox was created (thread 1).
When I check ListBoxItem.InvokeRequired from within thread 2 it is always false when ApartmentState.STA is set. When set to MTA I get an error. Thread 2 is a unique thread with different ID from thread 1.
What is frustrating is that at one point it was working fine, and then I changed some of the structure of the project and it has now stopped working (and I don't know which change caused this! It was a while ago).
This code is within a form class:
Option Strict Off
Option Explicit On
Imports System.Threading
Friend Class MainWinForm
[Code]....
this is going to be hard to explain but ill try. Question 1. Ok i have a list box with a few items, What i want for this example is to click a button and it will start on the first item and do: MsgBox ("this is item blah blah blah") then after that it will go to the next item and do the same and then the next and so on untill all have been done. The "blah blah" should be the item so if item was to say "hello" then the msgbox would say "this item is hello" I know this would be a lot of msgboxes to close, like if 50 items then thats 50 msgboxes to close, this is just for the example.
Question 2. Ok this is where ive tryed to learn but find it really hard (multithreading) Im wanting all to be multithreaded so all work at the same time, ive tryed a few times but the only way i see it is having a **** load of subs, like if i want it to use 10 threads then ill have to add the same code 10 times or somet, im not sure.
i have attempted all this and failed big time as my way was to get the first item and use that then remove it from the listbox BUT... with it being quite fast the 2nd 1 and 3rd 1 used the same item befor it was removed and to be honest i dont really want them removed. so my attempts took like 2-3 days that was a waste of time really. I Know this is a lot to ask but im in real need of it and these 2 things have driven me half mad.
In my application I have a listbox and SelectionMode should be MultiSimple because users need to see which items they selected. In another tab we have another listbox this one should show all the selection users had done in first tab. Private Sub
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How someone would select an item from a list box and click a button and have that item go into another listbox with it's price? I seem to be stuck on this part.
Here's my code:
I want to select the first option from the first listbox and I want to put it into another listbox along with the price of that item on the same line in the listbox. I can't seem to figure out how to that.
Public Class Form1
Const dcmPRICE_STRESS As Decimal = CDec(595.0)
Const dcmPRICE_TIME_MANAGMENT As Decimal = 695
[CODE]...
removing Listbox item from checked Listview item.The code I tried just errors out.
Private Sub ListView1_ItemCheck(sender As Object, e As System.Windows.Forms.ItemCheckEventArgs) Handles ListView1.ItemCheck
If (e.CurrentValue = CheckState.Unchecked) Then
ListBox1.Items.Add(Me.ListView1.Items(e.Index).Text)
ElseIf (e.CurrentValue = CheckState.Checked) Then
[Code]...
Is it possible to select an item in one listbox and then display the data of another listbox with the same indexed position? I am planning a project and this is something I would like to attempt but I haven't figured out how to do it.[code..]
I tried doing the above code but instead of displaying the listbox text the message box just returned false.
problem that i am facing is i want to add array of object as a single item in listbox. in vb6 i was using this Label1.Caption = Label1.Caption & Mid$ (strInput, intI, 1) & " " List1.AddItem (Label1.Caption) i was using label. caption to store object but not work in vs2008 because label.text only take text and left other values
View 18 RepliesI am trying to change an item in a selected item of a listbox.
View 1 RepliesI need some code that goes through each item in a listbox and executes a for next loop for each item
View 9 RepliesI have 2 listboxes on my form.Listbox 1 - populated with "available" field namesListbox 2 - populated with "selected" field names.There cannot be the same field name in both listboxes - it's either one of the other.The logic I was going to apply was to populate Listbox 1 with every field name ... and then as I populated Listbox with the field names which the user has already selected, remove the corresponding item from Listbox 1.
View 8 Replieshow to add listbox item to another,when listbox r created dynamically.
View 3 RepliesJust want to ask this. I have a jQuery that move listbox item to another listbox. An its working fine the item was remove. Sample: I remove item in listbox A and it was added to listbox B. But here is now the problem, when I tried to check each item in listbox A, I noticed that all items that was removed was still there. But i can see in my eyes that it was removed. but when I tried to run a code to check each items - all item that was removed was still there.
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I've got a TCP Listener running on a separate thread. I want to have it log the incoming and outgoing messages in a list on the form instead of in message boxes. I've been reading about multiple threads, and I know there's something extra I need to do because form controls are not thread safe.
Unfortunately I've tried several tutorials on delegates and invoking but it still doesn't seem to insert the log items to the list. I even spent $60 on this Mastering Visual Basic 2010 book to "Build Rich Client and Web Applications with Visual Basic", but there isn't a single chapter on how to handle multiple threads.
I have a "Form" with:
1- List Box
1- TextBox
3- Button
1- OpenFileDialog
1- SaveFileDialog
I want that clicking the btn1 it shows the OpenFileDialog and read file that it has got this structure: SKI10 1 71 0 0 18 101 19 0 29 101 30 0 40 101 41 0 50 101 51 0 62 101 63 0 81 101 82 0 95 101 2 0 0 95 165 3 0 1072 01 4 2 1 93 15
I want that it reads all Line of the File and it add an Item in ListBox for line.For example the first Item of the ListBox in this case is
SKI1
And the 2th Item is in this case.
0 1 7
I want using the StreamReader classes.And i want that when i click an Item of the ListBox it shows the Text in the TextBox and I can edit the Line and that clicking antoher button the Item will come updated with new Text of the TextBox.I have also another button for saving the Mod.I can use the AppendText and it create a new file writing ListBox1.Items line for line.
If SaveFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then Dim file_esistenteD As StreamWriter[code].....
I have a multiple form application with a listbox on each form. I want to be able to select an item in one listbox on one form and then click a button and it show up in a listbox on another form.
View 3 Replies'Form 1- start a new thread and declare a new second form. Have it invoke before adding an entry. as this apart from "CheckForIllegalCrossThreadCalls = false" is a workaround.
Code:
Public Class Form1
Dim t As New Thread(AddressOf startanew)
Private Sub startanew()
[Code].....
I have the following sub:Private Sub AmIintheListBox1(ByVal datatoenter As String)'Note.- ListboxItemsCount is a variable in the listbox1 change event
[Code]...
I do not know how to do the search of the datatoenter in a listbox with more then one item. If the item is already in the listbox then exit otherwise add it to the listbox.Threaddisplay adds the data to the listbox which I can do when there is no item yet.
CODE:
Is there anything I need to change about this code to let me insert list items to a listbox on the UI thread?
I want to write code that complete task of putting 0 to 1000 via thread in listbox. I want to start 10 threads at startup and complete task.
All threads should work equally. Each thread will write 100 numbers. First start from 0 to 100, second from 100 to 200, third from 200 to 300, so on upto 10th.
I have written code but it has problem.
Dim num As Int16
Dim startLoop As Int16
Dim endLoop As Int16
[CODE]...
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".
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
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
[Code]...
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.
[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
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