Porting a FileSystemWatcher app from CosoleApplication to Windows Forms

**hype261** · Jul 27 '10, 08:00 PM

Originally posted by Andraos

Hello,

I have the following app. It works great as a console app. It tracks any file changes, renames, or errors:

Code:

static void Main(string[] args)
	{
		FileSystemWatcher watcher = new FileSystemWatcher(@"C:\");

		watcher.NotifyFilter = (NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName);
		watcher.IncludeSubdirectories = true;

		watcher.Changed += new FileSystemEventHandler(OnChanged);
		watcher.Created += new FileSystemEventHandler(OnChanged);
		watcher.Deleted += new FileSystemEventHandler(OnChanged);
		watcher.Renamed += new RenamedEventHandler(OnRenamed);
		watcher.Error += new ErrorEventHandler(OnError);

		watcher.EnableRaisingEvents = true;

		Console.WriteLine("Press 'Enter' to exit...");
		Console.ReadLine();
	}

	private static void OnChanged(object source, FileSystemEventArgs e)
	{
		WatcherChangeTypes changeType = e.ChangeType;
		Console.WriteLine("File {0} {1}", e.FullPath, changeType.ToString());
	}

	private static void OnRenamed(object source, RenamedEventArgs e)
	{
		WatcherChangeTypes changeType = e.ChangeType;
		Console.WriteLine("File {0} {2} to {1}", e.OldFullPath, e.FullPath, changeType.ToString());
	}

	private static void OnError(object source, ErrorEventArgs e)
	{
		Console.WriteLine("An error has occurred.");
	}

I'm trying to port the same app to windows forms.
But the following code does not display anything in textbox1. any ideas?

Code:

string str = "";

		public Form1()
		{
			InitializeComponent();
		}

		private void Form1_Load(object sender, EventArgs e)
		{
			FileSystemWatcher watcher = new FileSystemWatcher(@"C:\");

			watcher.NotifyFilter = (NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName);
			watcher.IncludeSubdirectories = true;

			watcher.Changed += new FileSystemEventHandler(OnChanged);
			watcher.Created += new FileSystemEventHandler(OnChanged);
			watcher.Deleted += new FileSystemEventHandler(OnChanged);
			watcher.Renamed += new RenamedEventHandler(OnRenamed);
			watcher.Error += new ErrorEventHandler(OnError);
			watcher.EnableRaisingEvents = true;
		}

		private void OnChanged(object source, FileSystemEventArgs e)
		{
			str.Insert(str.Length, (e.FullPath + " " + e.ChangeType.ToString() + "\n"));
			textBox1.Invoke(new MethodInvoker(delegate { textBox1.Text = str; }));
		}

		private void OnRenamed(object source, RenamedEventArgs e)
		{
			str.Insert(str.Length, (e.OldFullPath + " " + e.FullPath + " to " + e.ChangeType.ToString() + "\n"));
			textBox1.Invoke(new MethodInvoker(delegate { textBox1.Text = str; }));
		}

		private void OnError(object source, ErrorEventArgs e)
		{
			str.Insert(str.Length, ("An error has occurred." + "\n"));
			textBox1.Invoke(new MethodInvoker(delegate { textBox1.Text = str; }));
		}

Any ideas at what I'm doing wrong?
Thanks

Is there a reason you are not just doing this?

Code:

textBox1.Text = str;

**Andraos** · Jul 27 '10, 09:36 PM

Hi Hype,

We can't directly assign 'str' to textbox1.Text. The following exception occurs:

"Cross-thread operation not valid: Control 'textBox1' accessed from a thread other than the thread it was created on."

Hence the <control>.Invok e() method.

Porting a FileSystemWatcher app from CosoleApplication to Windows Forms

Porting a FileSystemWatcher app from CosoleApplication to Windows Forms

Comment

Comment