Update a control in the UI from a different thread - c#

I have a M2MQTT client subscribed to a topic in the DashboardViewModel class. On message receive, the UI gets updated by calling Writelog.
public class DashboardViewModel : Object, IDashboardViewModel
{
private IDashboardView View { get; }
public DashboardViewModel(IDashboardView view)
{
View = view;
mqttClient = new MqttClient("localhost");
mqttClientId = Guid.NewGuid().ToString();
mqttClient.MqttMsgPublishReceived += mqttClient_MsgPublishReceived;
mqttClient.Subscribe(new string[] { "Home/Temperature" }, new byte[] { MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE });
mqttClient.Connect(mqttClientId);
//...
}
private void mqttClient_MsgPublishReceived(object sender, MqttMsgPublishEventArgs eventArgs)
{
string message = Encoding.UTF8.GetString(eventArgs.Message);
View.Writelog(message);
}
}
The textbox on FrmMain does not update; tbxLogs.InvokeRequired always returns false, i.e. tbxLogs.AppendText always executes. Any suggestions please?
public partial class FrmMain : Form, IDashboardView
{
private IDashboardViewModel dashboardViewModel = null;
private delegate void WriteLogCallback(string text);
public FrmMain()
{
InitializeComponent();
}
public void Writelog(string text)
{
if (tbxLogs.InvokeRequired)
{
WriteLogCallback callback = new WriteLogCallback(Writelog);
tbxLogs.Invoke(callback, new object[] { text });
}
else
{
tbxLogs.AppendText(text + "\n");
}
}
}

I think you need to use dispatcher :)
Dispatcher.CurrentDispatcher.BeginInvoke(DispatcherPriority.ApplicationIdle, new Action<String>(Writelog), message);
inside of this method
private void mqttClient_MsgPublishReceived(object sender, MqttMsgPublishEventArgs eventArgs)
{
string message = Encoding.UTF8.GetString(eventArgs.Message);
//here instead of View.Writelog(message);
}

Related

Problem with adding item to the list from another form

I would like to click "add button" to add contacts to the list of contacts in ClientApp, but nothing added to box, only to a list named users.
I want to see new usser nickname on the listbox. But when I evokes function AddContact from other form I don't see new usser on the listbox, from this same is good.
In atributes I see this cell, named "dwa".
Someone will help?
AddUsser:
public partial class NewUser: Form
{
...
public void New()
{
ClientApp.users.Add(new accounts(textBox1.Text, textBox2.Text));
ClientApp x = new KlientApp();
x.AddContact(textBox2.Text);
this.Hide();
}
}
ClientApp:
public partial class ClientApp: Form
{
...
public void AddContact(string nick)
{
contacts.BeginUpdate();
contacts.Items.Add(nick);
contacts.EndUpdate();
}
}
enter image description here
To Gellio Gao.
I sew ObjectDisposedException in private void Msg when I close program on go:
private void ShowMsg()
{
bool temp = true;
while( temp == true)
{
if(DateTime.Now.Second % 3 == 0)
{
Msg();
showed.WaitOne();
showed.Reset();
showed.WaitOne(1000);
}
}
}
private void Msg()
{
ClientLog.send_msg= "Wyswietl wiadomosci";
ClientLog.received.Reset();
Thread wątek = new Thread(new ThreadStart(AsynchronousClient.StartClient));
wątek.IsBackground = true;
wątek.Start();
ClientLog.received.WaitOne();
Invoke(new Action(() =>
{
if (ClientLog.send_msg!= "")
{
messages.AppendText(ClientLog.send_msg+ Environment.NewLine);
}
}));
showed.Set();
}
You should pass an instance of ClientApp to NewUser instead of creating a new instance inside of NewUser. Something like:
public partial class NewUser: Form
{
private ClientApp _client;
public NewUser(ClientApp client)
{
this._client = client;
}
................
public void New()
{
ClientApp.users.Add(new accounts(textBox1.Text, textBox2.Text));
this._client.AddContact(textBox2.Text);
this.Hide();
}
}
Update: Give a sample of using this._client.

Multiple class instances raising same event

I'm having trouble figuring out what is wrong with my C# code.
I'm trying to learn how to use ConcurrentQueue class in System.Collections.Concurrent namespace.
In order to do this, I'm creating 2 instances of the same class in different threads, passing to the constructors a different Listbox control.
I am expecting each class instance of EventGenerator to raise events at random intervals, updating the Listbox the were passed with randomly generated number, and adding that number to a ConcurrentQueue which is also passed to the constructor.
In my main thread, is the method to DeQueue the ConcurrentQueue of objects EnQueued to it by both spawned threads.
But what I'm getting is the 2 EnQueue Listboxes displaying the same data and the DeQueue Listbox seeming reporting to have deQueued them both.
I apologize if my description is not good enough, and my code follows, along with a link to an image of my form in case it might better help visualize what I'm trying to do...
Form
public partial class Form1 : Form
{
ConcurrentQueue<int> CQ;
EventGenerator eventGenerator1;
EventGenerator eventGenerator2;
public Form1()
{
InitializeComponent();
CQ = new ConcurrentQueue<int>();
eventGenerator1 = new EventGenerator(CQ, listBox1);
eventGenerator1.OnRandomEvent += new EventGenerator.RandomEventHandler(RandomEvent);
eventGenerator2 = new EventGenerator(CQ, listBox2);
eventGenerator2.OnRandomEvent += new EventGenerator.RandomEventHandler(RandomEvent);
}
private void RandomEvent(object sender, IncomingConnectionEventArgs e)
{
string s = e.Property_Int.ToString()
+ " "
+ e.Property_String;
UpdateListbox(s, e.LB);
}
private void UpdateListbox(string argstring, ListBox argListBox)
{
if (InvokeRequired)
{
Invoke(new Action<string, ListBox>(UpdateListbox), new object[] { argstring, argListBox });
return;
}
int n;
bool b = false;
//do
//{
b = CQ.TryDequeue(out n);
//} while (!b);
argListBox.Items.Add(argstring);
argListBox.SelectedIndex = argListBox.Items.Count -1;
listBoxDeQueue.Items.Add(n.ToString());
listBoxDeQueue.SelectedIndex = listBoxDeQueue.Items.Count - 1;
}
private void button_Start_Click(object sender, EventArgs e)
{
Thread methodThread1 = new Thread(new ThreadStart(TheThread1));
methodThread1.Start();
Thread methodThread2 = new Thread(new ThreadStart(TheThread2));
methodThread2.Start();
}
private void TheThread2()
{
eventGenerator2.Start();
}
private void TheThread1()
{
eventGenerator1.Start();
}
private void button_Stop_Click(object sender, EventArgs e)
{
eventGenerator1.Stop();
eventGenerator2.Stop();
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
eventGenerator1.Stop();
eventGenerator2.Stop();
}
}
IncomingConnectionEventArgs
class IncomingConnectionEventArgs : EventArgs
{
public System.Windows.Forms.ListBox LB;
public int Property_Int { get; set; }
public string Property_String { get; set; }
public IncomingConnectionEventArgs(int argInt, string argString,
System.Windows.Forms.ListBox lb)
{
LB = lb;
Property_Int = argInt;
Property_String = argString;
}
}
EventGenerator
class EventGenerator
{
public delegate void RandomEventHandler(
object sender,
IncomingConnectionEventArgs e);
public event RandomEventHandler OnRandomEvent;
public Random r = new Random();
public ListBox listBox;
public bool Generate = true;
public ConcurrentQueue<int> CQ;
public EventGenerator(ConcurrentQueue<int> argCQ, ListBox argListBox)
{
CQ = argCQ;
listBox = argListBox;
}
public void Start()
{
Generate = true;
while (Generate)
{
Thread.Sleep(r.Next(100, 2000));
RandomEvent();
}
}
public void Stop()
{
Generate = false; ;
}
public void RandomEvent()
{
if (OnRandomEvent == null)
{
return;
}
int n = r.Next(1000, 10000);
CQ.Enqueue(n);
IncomingConnectionEventArgs Args =
new IncomingConnectionEventArgs(n, "", listBox);
OnRandomEvent(this, Args);
}
}
The problem is with your use of Random. Unless you use a single instance of Random or explicitly seed each instance differently, the two threads calling Random.Next(...) will typically generate the same values.
A better way to seed your instance is this:
Random r = new Random(Guid.NewGuid().GetHashCode());

C# Custom event not working

public delegate void MessageReceiveEventHandler(MessageReceiveEventArgs e);
public event MessageReceiveEventHandler MessageReceiveEvent;
public class MessageReceiveEventArgs : EventArgs
{
public string Message { get; }
public MessageReceiveEventArgs(string Message)
{
this.Message = Message;
}
}
private void OnMessageReceiveEvent(string Message)
{
if (MessageReceiveEvent == null) return;
MessageReceiveEventArgs MessageREvent = new MessageReceiveEventArgs(Message);
MessageReceiveEvent(MessageREvent);
}
This is my event code. and i call event when my socket client receive message(data). but event not worked..
ClientSocket cs;
public Form1()
{
InitializeComponent();
cs = new ClientSocket();
cs.MessageReceiveEvent += Cs_MessageReceiveEvent1;
}
private void Cs_MessageReceiveEvent1(ClientSocket.MessageReceiveEventArgs e)
{
listBox1.Items.Add(e.Message);
}
I tried this.
I cannot see anywhere where you are raising the event. Try making the OnMessageReceiveEvent method public and then call it from the Form1 constructor.
public Form1()
{
InitializeComponent();
cs = new ClientSocket();
cs.MessageReceiveEvent += Cs_MessageReceiveEvent1;
cs.OnMessageReceiveEvent("Testing Event");
}

BackgroundWorker report progress from external Class?

I have a working solution that reports progress & text to a progress bar and a label on the applications's main form. I have now moved my worker methods to a class to they are accessible across multiple forms etc.
Within the worker methods are BW.ReportProgress() statements that push back the progress and text to the BackgroundWorker in the main form.
To give a better idea here is the file layout:
MainScreen.cs
List repSelected = new List();
XMLandRar xXMLandRar = new XMLandRar();
private void Rarbtn_Click(object sender, EventArgs e)
{
GetReps();
//Run worker
if (!CreateRarBW.IsBusy)
{
CreateRarBW.RunWorkerAsync();
}
}
//Worker
private void CreateRarBW_DoWork(object sender, DoWorkEventArgs e)
{
xXMLandRar.RarFiles(repSelected);
}
//Progress reporting
private void CreateRarBW_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progBar.Value = e.ProgressPercentage;
Statuslbl.Text = e.UserState.ToString();
}
Then my newly created Class that encompasses all of the worker methods and is to push progress to the main form.
XMLandRar.cs
public class XMLandRar
{
public void RarFiles(List repSelected)
{
int step = 100 / repSelected.Count();
int i = 0;
//Iterate through list and run rar for each
foreach (string rep in repSelected)
{
CreateRarBW.ReportProgress(i, "Raring files for " + rep);
DirectoryExists(rep);
ProcessRunner(rep);
i += step;
CreateRarBW.ReportProgress(i, "Raring files for " + rep);
}
}
}
The problem I am having is that in the XMLandRar class the CreateRarBW is not recognised (obviously) - how can I make a ReportProgress call to the BW in the main screen of the application?
Create an event in your XMLandRar class which you could subscribe to.
This way the XMLandRar class doesn't need to know or care about the UI or progressbar, it only cares about sending a message if anyone would listen. And there can also be more than one subscriber (let's say if you want to report to the background worker and a log, maybe)
Example:
private void Rarbtn_Click(object sender, EventArgs e)
{
GetReps();
//Run worker
if (!CreateRarBW.IsBusy)
{
// This should be done once, maybe in the contructor. Bind to new event.
xXMLandRar.ReportProgress += new EventHandler<XMLandRar.ProgressArgs>(xXMLandRar_ReportProgress);
CreateRarBW.RunWorkerAsync();
}
}
protected void xXMLandRar_ReportProgress(object sender, XMLandRar.ProgressArgs e)
{
// Call the UI backgroundworker
CreateRarBW.ReportProgress(e.Percentage, e.Message);
}
public class XMLandRar
{
// Event handler to bind to for reporting progress
public EventHandler<ProgressArgs> ReportProgress;
// Eventargs to contain information to send to the subscriber
public class ProgressArgs : EventArgs
{
public int Percentage { get; set; }
public string Message { get; set; }
}
public void RarFiles(List repSelected)
{
int step = 100 / repSelected.Count();
int i = 0;
//Iterate through list and run rar for each
foreach (string rep in repSelected)
{
// Report progress if somebody is listening (subscribed)
if (ReportProgress != null)
{
ReportProgress(this, new ProgressArgs { Percentage = i, Message = "Raring files for " + rep });
}
DirectoryExists(rep);
ProcessRunner(rep);
i += step;
// Report progress if somebody is listening (subscribed)
if (ReportProgress != null)
{
ReportProgress(this, new ProgressArgs { Percentage = i, Message = "Raring files for " + rep });
}
}
}
}
The sender object in the DoWork callback is the BackgroundWorker instance which is calling this callback.
This enables to use the instance and add it to your new XMLandRar class.
private void CreateRarBW_DoWork(object sender, DoWorkEventArgs e)
{
var worker = sender as BackgroundWorker.
xXMLandRar.RarFiles(repSelected, worker);
}
XMLandRar.cs
public class XMLandRar
{
public void RarFiles(List repSelected, BackgroundWorker worker)
{
// ...
}
}
Or you set the BackgroundWorkerinstance as a class property to the XMLandRar.
public class XMLandRar
{
protected BackgroundWorker mWorker;
public XMLandRar(BackgroundWorker worker) {
mWorker = BackgroundWorker;
}
public void RarFiles(List repSelected)
{
// Do something with {mWorker}
}
}
Or as mentioned in the comments, using events in the XMLandRar class.
XMLandRar.cs
public class XmlandRarCompletedEventArgs : EventArgs
{
public readonly bool Finished;
public readonly bool Canceled;
public XmlandRarCompletedEventArgs(bool finished)
{
Finished = finished;
Canceled = !finished;
}
}public class OnXmlandRarUpdateEventArgs : EventArgs
{
public readonly int Percentage;
public readonly string Message;
public XmlandRarCompletedEventArgs(int perc) :
this(perc, "") {
}
public XmlandRarCompletedEventArgs(int perc, string message)
{
Percentage = perc;
Message = message;
}
}
public delegate void OnXmlandRarDoWorkHandler(object o);
public delegate void OnXmlandRarUpdateHandler(object o, OnXmlandRarUpdateEventArgs args);
public delegate void OnXmlandRarCompleteHandler(object o, XmlandRarCompletedEventArgs args);
public class XMLandRar
{
public event OnXmlandRarDoWorkHandler OnDoWork;
public event OnXmlandRarUpdateHandler OnUpdate;
public event OnXmlandRarCompletedHandler OnComplete;
public void RarFiles(List repSelected)
{
TriggerDoWork();
int step = 100 / repSelected.Count();
int i = 0;
//Iterate through list and run rar for each
foreach (string rep in repSelected)
{
TriggerUpdate(i, "Raring files for " + rep);
DirectoryExists(rep);
ProcessRunner(rep);
i += step;
TriggerUpdate(i, "Raring files for " + rep);
}
TriggerComplete(true);
}
private void TriggerDoWork()
{
if (OnDoWork != null) {
OnDoWork(this);
}
}
private void TriggerUpdate(perc) {
}
if (OnUpdate != null) {
OnUpdate(this, new OnXmlandRarUpdateEventArgs(perc));
}
private void TriggerUpdate(perc, string message)
{
if (OnUpdate != null) {
OnUpdate(this, new OnXmlandRarUpdateEventArgs(perc, message));
}
}
private void TriggerComplete(bool finished)
{
if (OnComplete != null) {
OnComplete(this, new XmlandRarCompletedEventArgs(finished));
}
}
}
Usage:
private void CreateRarBW_DoWork(object sender, DoWorkEventArgs e)
{
var worker = sender as BackgroundWorker;
// Attach events to class
xXMLandRar.OnDoWork += delegate(object o) {
// ...
};
xXMLandRar.OnUpdate += delegate(object o, OnXmlandRarUpdateEventArgs args) {
// ...
};
xXMLandRar.OnComplete += delegate(object o, XmlandRarCompletedEventArgs args) {
// ...
};
xXMLandRar.RarFiles(repSelected, worker);
}
Hopefully without typos 'cause I'm in the office.
I have fixed errors in the code submitted and cleaned it up... This is a working sample that will help those that maybe couldn't understand the code since it was broken as it was... Although I would like to say that the intent and functionality of the code after it was cleaned up and enhanced is excellent.
This is working code that can get you started in your project for using a backGroundWorker thread for whatever you need.
Just modify this method -
public void RarFiles(List<string> repSelected)
To do whatever work you need. You will also have to modify the arguments you plan on using.. i.e. you may need a DataTable or some custom object...
You can modify the
public class OnXmlandRarUpdateEventArgs : EventArgs
For your needs.. that way when you get a callback.. you can update your main UI form with the changes made to those items..
You may need to do some tweaking.. but you see what i mean..
This is the Form Code.. Don't forget to create a button on the form...
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace ThreadSample
{
public partial class Form1 : Form
{
List<string> repSelected = new List<string>();
XMLandRar xXMLandRar = new XMLandRar();
BackgroundWorker CreateRarBW = new BackgroundWorker();
public Form1()
{
InitializeComponent();
repSelected = new List<string> { "asdf", "asdfsd", "h;ljj" };
CreateRarBW.DoWork += new DoWorkEventHandler(CreateRarBW_DoWork);
}
private void Rarbtn_Click(object sender, EventArgs e)
{
//GetReps();
//Run worker
if (!CreateRarBW.IsBusy)
{
// This should be done once, maybe in the contructor. Bind to new event.
xXMLandRar.ReportProgress += new EventHandler<XMLandRar.ProgressArgs>(xXMLandRar_ReportProgress);
CreateRarBW.RunWorkerAsync();
}
}
protected void xXMLandRar_ReportProgress(object sender, XMLandRar.ProgressArgs e)
{
// Call the UI backgroundworker
CreateRarBW.ReportProgress(e.Percentage, e.Message);
}
//private void CreateRarBW_DoWork(object sender, DoWorkEventArgs e)
//{
// var worker = sender as BackgroundWorker;
// xXMLandRar.RarFiles(repSelected, worker);
//}
private void CreateRarBW_DoWork(object sender, DoWorkEventArgs e)
{
var worker = sender as BackgroundWorker;
// Attach events to class
xXMLandRar.OnDoWork += delegate(object o)
{
// ...
MessageBox.Show("Hey ... Something is going on over there in the classLib .. " + o);
};
xXMLandRar.OnUpdate += delegate(object o, OnXmlandRarUpdateEventArgs args)
{
// ...
//foreach (object oo in args)
{
MessageBox.Show("Hey ... Something is going on over there in the classLib .. Message is " + args.Message + " and Percentage is " + args.Percentage);
}
};
xXMLandRar.OnComplete += delegate(object o, XmlandRarCompletedEventArgs args)
{
MessageBox.Show("Hey ... Something is going on over there in the classLib .. Canceled is " + args.Canceled + " and Finished is " + args.Finished);
// ...
};
xXMLandRar.RarFiles(repSelected);//, worker);
}
}
}
This is the class code. You can just create a class in your current project... Keep in mind that the CreateRarBW object is a BackGroundWorker instance... (Wasn't included above..)
using System;
using System.Collections.Generic;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.IO;
using System.Diagnostics;
using System.Threading;
namespace ThreadSample
{
public class XmlandRarCompletedEventArgs : EventArgs
{
public readonly bool Finished;
public readonly bool Canceled;
public XmlandRarCompletedEventArgs(bool finished)
{
Finished = finished;
Canceled = !finished;
}
}
public class OnXmlandRarUpdateEventArgs : EventArgs
{
public readonly int Percentage;
public readonly string Message;
public OnXmlandRarUpdateEventArgs(int perc) : this(perc, "")
{
}
public OnXmlandRarUpdateEventArgs(int perc, string message)
{
Percentage = perc;
Message = message;
}
}
public delegate void OnXmlandRarDoWorkHandler(object o);
public delegate void OnXmlandRarUpdateHandler(object o, OnXmlandRarUpdateEventArgs args);
public delegate void OnXmlandRarCompleteHandler(object o, XmlandRarCompletedEventArgs args);
public class XMLandRar // : BackgroundWorker
{
// Event handler to bind to for reporting progress
public EventHandler<ProgressArgs> ReportProgress;
// Eventargs to contain information to send to the subscriber
public class ProgressArgs : EventArgs
{
public int Percentage { get; set; }
public string Message { get; set; }
}
public event OnXmlandRarDoWorkHandler OnDoWork;
public event OnXmlandRarUpdateHandler OnUpdate;
public event OnXmlandRarCompleteHandler OnComplete;
public void RarFiles(List<string> repSelected)
{
TriggerDoWork();
int step = 100 / repSelected.Count();
int i = 0;
//Iterate through list and run rar for each
foreach (string rep in repSelected)
{
TriggerUpdate(i, "Raring files for " + rep);
//DirectoryExists(rep);
//ProcessRunner(rep);
i += step;
TriggerUpdate(i, "Raring files for " + rep);
}
TriggerComplete(true);
}
private void TriggerDoWork()
{
if (OnDoWork != null)
{
OnDoWork(this);
}
}
private void TriggerUpdate(int perc)
{
if (OnUpdate != null)
{
OnUpdate(this, new OnXmlandRarUpdateEventArgs(perc));
}
}
private void TriggerUpdate(int perc, string message)
{
if (OnUpdate != null)
{
OnUpdate(this, new OnXmlandRarUpdateEventArgs(perc, message));
}
}
private void TriggerComplete(bool finished)
{
if (OnComplete != null)
{
OnComplete(this, new XmlandRarCompletedEventArgs(finished));
}
}
}
}

Singleton Bindable Controls While Tasking/Multi-Threading

before posting the question i did my research for 10 days so really hope someone can shed some light into solving this issue.
The issue is that any bindable control, does not update once the binding list from singleton class is changed. This is a common issue on multi-threaded apps. Most if not all solutions offer suggestions where the bindlinglist or collection is initialized from parent thread, and then some invocation to be made. Not what i'm looking for. The same issue persist if static class is used instead of singleton.
Basically, the application triggers some Tasks, which in turn create object(s) on different business classes. These objects post messages into the bindinglist, which should update the UI listbox, but does not. And yes, the message object is in the list, and binding after the TASK finished works (items displayed). Locking/unlocking object(s) access is also not an issue.
Appreciate any suggestions/solutions
A trimmed down version of business objects:
namespace MyNameSpace
{
public class Message
{
private string messageSummary;
public Message() { }
public string MessageSummary
{
set { messageSummary = value; }
get { return messageSummary; }
}
}
}
A trimmed down version of another class doing some ops:
namespace MyNameSpace
{
public class WorkDoingClass
{
public WorkDoingClass() { }
public void DoSomeWork()
{
//some routines
Message messageObj = new Message();
messageObj.MessageSummary = "DoSOmrWork Finished";
}
public void DoSomeOtherWork()
{
//some routines
Message messageObj = new Message();
messageObj.MessageSummary = "DoSomeOtherWork Finished";
AllMessages.Instance.AllMessagesBindingList.Add(messageObj);
}
}
}
Singleton:
namespace MyNameSpace
{
public sealed class AllMessages
{
private static readonly AllMessages _instance = new AllMessages();
private BindingList<Message> _allMessagesBL;
public WorkDoingClass() { _allMessagesBL = new BindingList<Message>(); }
public static AllMessages Instance
{
get { return _instance; }
}
public BindingList<Message> AllMessagesBindingList
{
get { return _allMessagesBL};
}
}
}
This is also a trimmed down version from where calls start:
namespace MyNameSpace
{
public partial class Form1 : Form
{
private Task _TaskSqlData;
private CancellationTokenSource cTokenSourceSql;
public Form1()
{
InitializeComponent();
listBox1.DataSource = AllMessages.Instance.AllMessagesBindingList;
listBox1.DisplayMember = "MessageSummary";
}
private void button1_Click(object sender, EventArgs e)
{
cTokenSourceSql = new CancellationTokenSource();
var tokenSqlData = cTokenSourceSql.Token;
if (this._TaskSqlData != null)
{
if (this._TaskSqlData.Status == TaskStatus.Running)
this.cTokenSourceSql.Cancel();
this._TaskSqlData.Dispose();
this._TaskSqlData = null;
}
_TaskSqlData = Task.Factory.StartNew(()
=> StartDoingWork(this, tokenSqlData, null), tokenSqlData);
}
public void StartDoingWork(object sender, CancellationToken ct, EventArgs e)
{
if (ct.IsCancellationRequested)
ct.ThrowIfCancellationRequested();
WorkDoingClass work = new WorkDoingClass();
work.DoSomeOtherWork();
}
Your problem is that the thread(the main UI thread) making the listbox is different from the thread(the worker thread) modifying the collection.
Try the following code. It could solve your issue. I use SynchronizationContext to synchronize the two threads, which serves as the same function with Control.Invoke().
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
private Task _TaskSqlData;
private CancellationTokenSource cTokenSourceSql;
WorkDoingClass _work;
public Form1()
{
InitializeComponent();
listBox1.DataSource = AllMessages.Instance.AllMessagesBindingList;
listBox1.DisplayMember = "MessageSummary";
_work = new WorkDoingClass(SynchronizationContext.Current);
}
private void button1_Click(object sender, EventArgs e)
{
cTokenSourceSql = new CancellationTokenSource();
var tokenSqlData = cTokenSourceSql.Token;
if (this._TaskSqlData != null)
{
if (this._TaskSqlData.Status == TaskStatus.Running)
this.cTokenSourceSql.Cancel();
this._TaskSqlData.Dispose();
this._TaskSqlData = null;
}
_TaskSqlData = Task.Factory.StartNew(()
=> StartDoingWork(this, tokenSqlData, null), tokenSqlData);
}
public void StartDoingWork(object sender, CancellationToken ct, EventArgs e)
{
if (ct.IsCancellationRequested)
ct.ThrowIfCancellationRequested();
_work.DoSomeOtherWork();
}
}
public class Message
{
private string messageSummary;
public Message() { }
public string MessageSummary
{
set { messageSummary = value; }
get { return messageSummary; }
}
}
public class WorkDoingClass
{
private SynchronizationContext _syncContext;
public WorkDoingClass() { }
public WorkDoingClass(SynchronizationContext _syncContext)
{
// TODO: Complete member initialization
this._syncContext = _syncContext;
}
public void DoSomeWork()
{
//some routines
Message messageObj = new Message();
messageObj.MessageSummary = "DoSOmrWork Finished";
}
public void DoSomeOtherWork()
{
_syncContext.Send(DoWork, null);
}
private static void DoWork(object arg)
{
//some routines
Message messageObj = new Message();
messageObj.MessageSummary = "DoSomeOtherWork Finished";
AllMessages.Instance.AllMessagesBindingList.Add(messageObj);
}
}
public sealed class AllMessages
{
private static readonly AllMessages _instance = new AllMessages();
private BindingList<Message> _allMessagesBL;
public AllMessages() { _allMessagesBL = new BindingList<Message>(); }
public static AllMessages Instance
{
get { return _instance; }
}
public BindingList<Message> AllMessagesBindingList
{
get { return _allMessagesBL; }
}
}
}

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