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Thread: List.Add not set to an instance of an object

  1. #1
    Join Date
    Sep 2018
    Posts
    38

    List.Add not set to an instance of an object

    Hi, I've got a method where I'm trying to add an object to a list, and Visual Studio debug gives me an error that what I'm trying to add is "not set to an instance of an object". I set my list to be List(Of Object), and also set my variable to a FileSystemWatcher object, but still get the error. Breakpoint just tells me the same thing. Here's my code...if someone has any ideas why I'm getting this error I'm open to suggestions. I've also tried setting everything to string type, but still get the same debug message. Here's my code:

    Code:
    Public FSWList As List(Of Object)
    
    Public Sub SetupFileWatcher(fswPath As String, fswPlan As String, fswFilter As String, SyncObject As Form)
    
                Dim fsw As FileSystemWatcher = New FileSystemWatcher(fswPath)
    
                If fswPath.Length = 0 Then
                    Return
                End If
    
                fsw.BeginInit()
                fsw.SynchronizingObject = SyncObject
                fsw.InternalBufferSize = 32768
                fsw.IncludeSubdirectories = True
                fsw.Filter = fswFilter
                fsw.Path = fswPath
                fsw.NotifyFilter = NotifyFilters.FileName Or NotifyFilters.CreationTime
    
                AddHandler Me.Created, New FileSystemEventHandler(AddressOf Me.OnCreated)
                AddHandler Me.Deleted, New FileSystemEventHandler(AddressOf Me.OnDeleted)
    
                fsw.EnableRaisingEvents = True
                fsw.EndInit()
    
    'this is the line that is giving me the error
                FSWList.Add(fsw)
    
            End Sub

    Thanks for any ideas.

  2. #2
    Arjay's Avatar
    Arjay is online now Moderator / MS MVP Power Poster
    Join Date
    Aug 2004
    Posts
    12,838

    Re: List.Add not set to an instance of an object

    It's not initialized. Initialize it with New in the class constructor.

  3. #3
    Join Date
    Oct 2018
    Posts
    2

    Re: List.Add not set to an instance of an object

    You'll need to ensure that the collection isn't null and is properly instantiated prior to adding an object to it.
    gmail sign up

  4. #4
    Join Date
    Sep 2018
    Posts
    38

    Re: List.Add not set to an instance of an object

    Thanks y'all, that was exactly the problem. It never ceases to amaze me how basic things like that make the difference. Hey Arjay, I don't know if that code I posted was good for you to review on our discussion of binding. If you still want me to make a solution for you to look at before we continue, let me know. I searched on the net for some material about it, but didn't find anything. Wasn't really sure of what I was looking for. The book I've got on Visual Studio talks about collections in general, but still leaves a lot to be learned.

    Appreciate the input folks...

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