My.Settings save Combobox Items?

[Dragnorian]

Hello! I have been working on code and wanna store Combo Box items in Application settings since that seems easiest. I have made the variable I made in the settings(comiclist) as Strings Collection basically. Anyways, when the user first loads the application, I have a form that comes up and allows the user to input values to populate the combobox. The code I have for them saving the values first is:

    Private Sub txtData_KeyDown(sender As Object, e As KeyEventArgs) Handles txtData.KeyDown
        If (e.KeyCode = Keys.Enter) Then
             My.Settings.ComicList.Add(txtdata.Text)
        End If
    End Sub

But the error I get is 'Object reference not set to an instance of an object.'
I figured to add the .ToString() at the end of My.Settings.ComicList.Add(txtdata.Text) but nah, that didn't work. This is the first time I've worked with String Collection so anything I am doing wrong?

[Sitten Spynne]

My.Settings is one of those things I gave up on a long time ago because I was already used to maintaining my own settings files and I kept having to spend time on little warts that didn't make any sense.

In this case: if you don't pre-populate a StringCollection setting with any values, it has no values. As far as My.Settings is concerned, "no values" means it shouldn't bother making a StringCollection instance, which means it's Nothing by default.

So to be safe, your application should expect this and protect itself:

Protected Overrides Sub OnShown(e As EventArgs)
    MyBase.OnShown(e)

    If My.Settings.TestSetting Is Nothing Then
        My.Settings.TestSetting = New Specialized.StringCollection()
        My.Settings.Save()
    End If
End Sub

That's not the only way to do it, but it's a good way to make sure at startup the collection exists.

[Dragnorian]

Alright, thank you man! May I ask, how did you do that Protected Overrides?

[Sitten Spynne]

I know that Shown is an event forms implement. The pattern Microsoft follows is that for every event, there is a Protected Overridable On<EventName>() method you can override instead of messing with setting up an event handler on yourself. So I typed "Overrides OnShown" and Intellisense filled in the rest for me.

[Dragnorian]

Oh. That is interesting. Thank you for the help! It all works good now for that issue. Thanks again mate, have a good day!