passing parameter to an event handler [duplicate]

Question

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) {  } 

Answer 1

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) }