Cannot implicitly convert type 'System.EventHa

问题:

I have read already a few threads about this, but I still don't know how to solve it in my case. I come from Java and mostly new to C#

I want to attach listener when animation finishes:

myStoryBoard.Completed += new EventHandler(onMyStoryBoardCompleted);

And:

private void onMyStoryBoardCompleted(object sender, EventArgs e)
{       
}

And I get the error in the title. I tried:

 myStoryBoard.Completed += new EventHandler<object>(onMyStoryBoardCompleted);

But then I get:

no overload for 'onMyStoryBoardCompleted' matches delegate 'System.EventHandler<object>'

So it seems that the signature is not compatible with EventHandler<object> and I couldn't find how to make it compatible, I also don't know if this approach is correct.

I read

Understanding events and event handlers in C#

C# Dynamic template implicit conversion error from System.EventHandler to System.EventHandler<TEventArgs>

defining event handler for Tick event of DispatcherTimer in windows 8 app

But still don't find the solution for this case.

Thanks in advance.

回答1:

Try:

private void onMyStoryBoardCompleted(object sender, object e)
{ }

And subscribe using the generic EventHandler<object>:

myStoryBoard.Completed += new EventHandler<object>(onMyStoryBoardCompleted);

Of course, this goes against the .NET Framework convention that the second argument to an event handler should be an instance of EventArgs (or a class derived thereof). I am assuming that you are running on another framework, such as Windows 8 Metro, whose Timeline class defines a Completed event with an EventHandler<object> signature.