VB.Net - FileSystemWatcher

The FileSystemWatcher class is used to create a function that watches activities being performed on files sitting in a folder. When running it will throw an event whenever a file is added, changed, deleted, or renamed.

Actually I found several suprisingly good websites.

• http://stackoverflow.com/questions/26015325/checking-for-new-files-in-a-folder - someone posted a good example.
• https://msdn.microsoft.com/en-us/library/system.io.filesystemwatcher(v=vs.110).aspx - Microsofts page.

Note: I created a form, and placed the code within the form. I did this because If I created a main() routine, it would execute, and then terminate and the FileSystemWatcher would not be running. By creating the form I know that the FileSystemWatcher is functioning because the window is open.

On the form I added a textbox control:

• A directory to watch named ‘txtDir’. it is populated with the folder being watched

Here is a stripped down version of the code behind the form

Imports System
Imports System.IO
Imports System.Diagnostics
Imports System.Windows.Forms

Public Class theMain
	Public watchfolder As FileSystemWatcher

	Private Sub theMain_Load(sender As Object, e As EventArgs) Handles MyBase.Load
		Dim cmdline As String _
			= Command()
		Dim cmd() As String _
			= cmdline.Split(" ")

		Console.WriteLine("Directory Watch Utility")
		Console.WriteLine("Creates a log of files added, modified, created, " _
			& "deleted, or renamed for a specific directory")
		Console.WriteLine("")
		Console.WriteLine("Usage")
		Console.WriteLine("  DirWatch DirectoryToWatch ")
		Console.WriteLine("")
		If cmd.Length < 2 Then
			End
		End If
		txtDir.Text = cmd(0)

		watchfolder = New System.IO.FileSystemWatcher()
		watchfolder.Path = txtDir.Text
		watchfolder.NotifyFilter = IO.NotifyFilters.DirectoryName
		watchfolder.NotifyFilter = watchfolder.NotifyFilter Or
			IO.NotifyFilters.FileName
		watchfolder.NotifyFilter = watchfolder.NotifyFilter Or
			IO.NotifyFilters.Attributes
		'AddHandler watchfolder.Changed, AddressOf logchange  ' TMI
		AddHandler watchfolder.Created, AddressOf logchange
		AddHandler watchfolder.Deleted, AddressOf logchange
		AddHandler watchfolder.Renamed, AddressOf logrename
		watchfolder.EnableRaisingEvents = True

		Log("Dir Watcher Program Started - " & txtDir.Text)
	End Sub


	Private Sub logchange(ByVal source As Object _
					, ByVal e As System.IO.FileSystemEventArgs)

		If e.ChangeType = IO.WatcherChangeTypes.Changed Then
			Log(e.FullPath & ", modified")
		End If
		If e.ChangeType = IO.WatcherChangeTypes.Created Then
			Log(e.FullPath & ", created")
		End If
		If e.ChangeType = IO.WatcherChangeTypes.Deleted Then
			Log(e.FullPath & ", deleted")
		End If
	End Sub
	Public Sub logrename(ByVal source As Object _
					, ByVal e As System.IO.RenamedEventArgs)

		Log(e.OldName & ", renamed to " & e.Name)
	End Sub

	Public Sub Log(message As String)
		Console.WriteLine(DateTime.Now.ToString & ", " + message)
	End Sub

	Private Sub theMain_FormClosing(sender As Object _
					, e As FormClosingEventArgs) Handles Me.FormClosing
		Log("Dir Watcher Program Ending - " & txtDir.Text)
	End Sub
End Class	

My full version sends the output to a log file - but that small bit of extra code was not needed for this example.