Porting a FileSystemWatcher app from CosoleApplication to Windows Forms

[Andraos]

Hello,

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

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?

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

[hype261]

@Andraos
Is there a reason you are not just doing this?

textBox1.Text = str;

[Andraos]

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>.Invoke() method.