Cross Thread Exception in my event handler

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I am getting a Cross Thread excpetion here as i am trying to access the control other than the thread it has been created. I tried achieving this using System.ComponentModel.BackgroundWorker class. Beacuse some internal issue in our app, i cannot use this. Please help

private System.Timers.Timer m_SystemTimer;
private Form m_ProgressBox;

public MyClass()
{
InitializeComponent();

m_SystemTimer = new System.Timers.Timer();
m_SystemTimer.Interval = 3000;
m_SystemTimer.AutoReset = false;

m_SystemTimer.Elapsed += new System.Timers.ElapsedEventHandler(m_SystemTimer_Elapsed);
}

private void m_SystemTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
if (m_ProgressBox == null)
{
m_ProgressBox = new Form();
m_ProgressBox.Show();
}
}

private void MyEventHandler1(object sender, EventArgs e)
{
m_SystemTimer.Start();
}

private voMyEventHandler2(object sender, EventArgs e)
{
m_ProgressBox.Close(); // throws a cros thread exception here
}

Posted 2-Apr-14 0:57am

priyabs

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[no name] 2-Apr-14 8:54am

Hi.Thanks for the response. I want my timer tick to happen only once thats why i have set m_SystemTimer.AutoReset = false;
In this case Your solution will not be helpful.In my case, i dont have any Form, to call BeginInvoke on the control.

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Raul Iloc · Answer 1 · 2014-04-02T01:18:00

1.You cannot access that form because was created in other thread.

2.You should design a new solution for intercommunicate between thread, for example to use a class member name closeProgress that will be set on true from your voMyEventHandler2 and will be checked in your m_SystemTimer_Elapsed and if is true and the form is shown to close the form and put the variable on false.

OriginalGriff · Answer 2 · 2014-04-02T01:06:00

Solution 1

Since you don't show us the code where you add the handlers or signal the events I can only assume that you are raising your events from a different thread - in which case you cannot access UI controls without Invoking them.

C#

if (InvokeRequired)
    {
    Invoke(new MethodInvoker(delegate { m_ProgressBox.Close(); }));
    }
else
    {
    m_ProgressBox.Close();
    }

Posted 2-Apr-14 1:06am

OriginalGriff

Comments

[no name] 2-Apr-14 8:59am

Thanks for the response. I have just simulated my requirement through Button1 click for shoing Progress and after some time, i click Button2 to close progressBox. I n my actual scenarion i will only get 2 event handlers to do the above functionlaity.
On What control do i need to do Invoke the progressBox? (the solution you proposed).

Here is full program, but please note that i dont have access to Form in my real scenario.

public partial class Form1 : Form
{
private System.Timers.Timer m_SystemTimer;
private Form m_ProgressBox;

public Form1()
{
InitializeComponent();

m_SystemTimer = new System.Timers.Timer();
m_SystemTimer.Interval = 3000;
m_SystemTimer.AutoReset = false;

m_SystemTimer.Elapsed += new System.Timers.ElapsedEventHandler(m_SystemTimer_Elapsed);
}

private void m_SystemTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
// Timer starts after 3 seconds and happend only once.
if (m_ProgressBox == null)
{
m_ProgressBox = new Form();
m_ProgressBox.Show();
}
}

private void button1_Click(object sender, EventArgs e)
{
m_SystemTimer.Start();
}

private void button2_Click(object sender, EventArgs e)
{
m_ProgressBox.Close(); // throws a cros thread exception here
}
}

Cross Thread Exception in my event handler

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