passing parameter to an event handler [stackoverflow]

Q:

i want to pass my List<string> as parameter using my event

public event EventHandler _newFileEventHandler;
    List<string> _filesList = new List<string>();

public void startListener(string directoryPath)
{
    FileSystemWatcher watcher = new FileSystemWatcher(directoryPath);
    _filesList = new List<string>();
    _timer = new System.Timers.Timer(5000);
    watcher.Filter = "*.pcap";
    watcher.Created += watcher_Created;            
    watcher.EnableRaisingEvents = true;
    watcher.IncludeSubdirectories = true;
}

void watcher_Created(object sender, FileSystemEventArgs e)
{            
    _timer.Elapsed += new ElapsedEventHandler(myEvent);
    _timer.Enabled = true;
    _filesList.Add(e.FullPath);
    _fileToAdd = e.FullPath;
}

private void myEvent(object sender, ElapsedEventArgs e)
{
    _newFileEventHandler(_filesList, EventArgs.Empty);;
}

and from my main form i want to get this List:

void listener_newFileEventHandler(object sender, EventArgs e)
{

}

A:

Make a new EventArgs class such as:

public class ListEventArgs : EventArgs
    {
        public List<string> Data { get; set; }
        public ListEventArgs(List<string> data)
        {
            Data = data;
        }
    }

And make your event as this:

public event EventHandler<ListEventArgs> NewFileAdded;

Add a firing method:

protected void OnNewFileAdded(List<string> data)
{
    var localCopy = NewFileAdded;
    if (localCopy != null)
    {
        localCopy(this, new ListEventArgs(data));
    }
}

And when you want to handle this event:

myObj.NewFileAdded += new EventHandler<ListEventArgs>(myObj_NewFileAdded);

The handler method would appear like this:

public void myObj_NewFileAdded(object sender, ListEventArgs e)
{
       // Do what you want with e.Data (It is a List of string)
}