user-defined Event has a exception

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Winform Application.
I defined a Event:

C#

public delegate void TestEventHandler();
        public static event TestEventHandler OnTestEvent;

private void button1_Click(object sender, EventArgs e)
        {
            if (OnTestEvent != null)
            {
                OnTestEvent();
            }
        }

void Form1_OnTestEvent()
        {
           throw new NotImplementedException("12345");
        }

And I Catch the exception with UnhandledException.
But it did not Catch the Exception.

when I do not catch exception with "try/catch", how i to do?

Posted 28-Mar-11 2:22am

jason_mf

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[no name] 28-Mar-11 8:30am

Your question is not clear. Where are you trying to catch the exception?

3 solutions

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#realJSOP · Answer 1 · 2011-03-28T02:33:00

Do this:

C#

public delegate void TestEventHandler(); 
public static event TestEventHandler OnTestEvent = delegate{};

At that point, you an just call OnTestEvent() ewithout the if block.

By the way, you really should have - at the VERY least) the following parameters (even if you don't use them right away):

C#

public delegate void TestEventHandler(object sender, EventArgs e);

In fact, your *should* define your own MyEventArgs class (must inherit from EventArgs) so that you can pass parameters to the event handler.

Alan N · Answer 2 · 2011-03-28T02:40:00

Solution 2

You seem to imply that you have implemented a handler for
System.AppDomain.CurrentDomain.UnhandledException which will trap unhandled exceptions occurring on non UI threads.

Use System.Windows.Forms.Application.ThreadException to trap UI thread exceptions.

Alan.

Posted 28-Mar-11 2:40am

Alan N

Olivier Levrey · Answer 3 · 2011-03-28T03:04:00

If you want to catch every exceptions in your program, you can do something like that:

C#

static class Program
{
    [STAThread]
    static void Main()
    {
        InitUnknownExceptionHandlers();
        ...
    }

    static void InitUnknownExceptionHandlers()
    {
        //exceptions thrown by the main thread (UI thread)
        Application.ThreadException +=
            new ThreadExceptionEventHandler(UIThreadUnhandledException);
        Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);
        //exceptions thrown by other threads
        AppDomain.CurrentDomain.UnhandledException +=
            new UnhandledExceptionEventHandler(OtherThreadUnhandledException);
    }
    /// <summary>
    /// This function is called if an exception is thrown from the main thread (UI thread).
    /// </summary>
    static void UIThreadUnhandledException(object sender, ThreadExceptionEventArgs t)
    {
        //do something with the exception.
        MessageBox.Show("An unhandled exception occured:" + Environment.NewLine + t.Exception.Message);
        //you can also use ex.StackTrace to know where the exception was thrown
        //your program can still continue
    }
    /// <summary>
    /// This function is called if an exception is thrown from another thread.
    /// You can display a message to the user or do whatever you want here,
    /// but your application can't continue after: the framework will shut it down.
    /// </summary>
    static void OtherThreadUnhandledException(object sender, UnhandledExceptionEventArgs e)
    {
        Exception ex = (Exception)e.ExceptionObject;
        MessageBox.Show("An unhandled exception occured and the application will be terminated:" +
             Environment.NewLine + ex.Message);
        //you can also use ex.StackTrace to know where the exception was thrown
    }
}

user-defined Event has a exception

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