.NET Multithreading / Calling Invoke On A UI Control From A Class In A Separate Class File?

May 13, 2011

Example:

Two files - TestClass.vb, myForm.vb

TestClass.vb looks as follows:

Imports System.Threading
Public Class TestClass
Private myClassThread As New Thread(AddressOf StartMyClassThread)

[code]....

The result:Application runs, no errors or exceptions.Displayed is the listbox and the Start button.I press the start button and a msgbox says "Not Invoked" as expected and upon clicking OK to that msgbox "Start Button Pressed" is added to the Output listbox control.Immediately following that the msgbox pops up again and says "Not Invoked". I was expecting "Invoked" as a separate thread is trying to use the Output listbox control.Of course this results in the Output.Items.Add being attempted which results in no visible result as the thread is not allowed to directly update the UI control.

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Multithreading - Cross Thread Invoke From Class?

Jan 24, 2012

I am making use of a serial port in a class. I am raising an event from that class to my form calling the class. Event contains data received... I wish to simply populate a textbox from the raised event.Now I am not specifically creating a seperate thread, but I get the normal crossthreading error when trying to update my textbox on the UI, so my assumption is that the serial port and its internal methods probably creates its own threads...Regardless, I am a bit confused as to how to properly implement an invoke, from my main form, pointing to the thread in the instantiated class...

Dim WithEvents tmpRS232 As New clsRS232
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tmpRS232.Set_com_port("COM8", 38400)

[code]....

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E.g. I have a class:

Namespace Common
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Public Class BClass

[code]....

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Protected
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[code]....

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I have a listbox in separate class like this [code]

[Code]...

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I've got the following code:

[code]...

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<div sizcache="0" sizset="0">

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[Code]...

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[CODE]...

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[CODE]...

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Public Class Form1
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[Code]....

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is there a way to invoke that method ?

PS/ The project is written in vbnet, but I think the solution is the same in c#.

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[Code]...

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[Code]...

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Right now I have a Email class that has all the properties of an email to send it, and then a SendEmail function which takes those properties and uses them in the following

Public Function SendEmail()
'Exception handling
Try

[Code]....

The loop goes through each email in the array to process its email, however with the multithreaded function I cannot call

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So how do I call an objects method when its on a different thread?

And I'm making it multithreaded so I can easily pause the process, and because the program freezes when the send() function is working, this would resolve that.

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so I used to mess around with C#, just a little. And someone had helped me make a class for Visual C# that was supposed to do the math parts for "internal structure" - which the program used for a part of its calculations and screen... Basically there were 2 options. Endo-Steel and Standard. The user would use a updownbox to determine weight of the machine and then internal structure was a % of that total. If it was standard then it was 10% of the overall weight, if it was Endo-Steel then it was 50% of standard (so 5% of total weight) rounded to next 0.5 (so .25 was .5, 1.25 was 1.5, 1.75 was 2.0, etc). I have the code for the C# class file for it, but want to make it in VB.

[Code]...

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Good evening folks, I'm building a program that is threaded. While I can get the thread to work no problem, I can not seem to add pages to my tabcontrol from the class I'm using. Any idea's on what I'm doing wrong?frmMain is loaded first. Then the idea is to load the other tabpages using a separate thread as they take awhile.[code]

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Jan 20, 2011

I am having following Projects

ClassLibrary1
Public Class Class1
Public Sub MyMethod()

[code].....

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Feb 11, 2011

I don't want my application's main form to be displayed when it opens; I just want the notifyicon control in it to show in the taskbar.This is the code I have been using:

Module:
Code:
Module mdlStartup
Public Sub Main()

[Code]...

The NotifyIcon control is in my frmMain. However, when I run my program I get mulitple instances of the Notify Icon being displayed. I even get two frmMains getting launched if I try clicking the other tray icon that has been made. I'm guessing this has to do with the New instance.If that's the problem, is there a way I can move the notifyicon control to some completely separate class?

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Mar 12, 2011

I have created a class for Socket reads so I can create sockets on command. Due to performing a socket read, the program will freeze waiting for incoming data due to being on a single thread. So I created a separate thread for the reading of the sock and attempt to invoke an event to prevent multi-threading errors.

But I am getting an error when trying to Invoke: "Invoke or BeginInvoke cannot be called on a control until the window handle has been created."

How can I fix this or is there a better way to read a sock without freezing the thread?

Class for Sockets:

Option Explicit On
Option Strict On

Imports System.Text

[CODE]...

Calling form code example:

Private WithEvents Socks As clsSock

Private Sub Sock_Connected(ByVal state As String) Handles Socks.Connected
MsgBox("Connected - " & state)

[CODE]...

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If Class X is within the scope of Class Y, is X a subclass of Y?If Class A is a sub Class of B, then is Class B considered a super class of A?if Class C inherits Class D is Class D a superclass or parent of Class C?if Class E extends Class F then we can consider Class E a child of F?if Class G inherits Class H and is within the scope of Class I then who is the parent of Class G? Classes that inherits Class J and classes that are within Class J are all sub classes of Class J?

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I am trying to get a handle on SyncLock and multithreading, but I am having some trouble wrapping my head around exactly how it should be implemented. I have a Public Class Utilities with a many Shared Functions. I want to make sure that each function can only be executed when there are no other concurrent calls to the same function. So If I have 2 functions, A and B in a Public Class Utilities, what is the syntax so that a function "locks" while it is being executed, preventing any subsequent calls until the "locking" thread has completed?

CODE

Public Class Utilities

Public Shared Function A (ByRef i As Integer) As Integer

[CODE].............................

I know I need to wrap the statements of execution in a SyncLock block, but I am unsure of the scope of the parameter used with SyncLock...is it private to the function, class, etc? Can the same object be used to lock both functions if they are independent?

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