[RESOLVED] Add item to a combobox items collection at run time

[jmcilhinney]

Personally, as a fan of data-binding, I would probably do it like this:

Public Class Form1
 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        'Bind the settings collection via a BindingSource.
        BindingSource1.DataSource = My.Settings.ComboBox1Items
        ComboBox1.DataSource = BindingSource1
    End Sub
 
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        'Add a new item from a TextBox.
        BindingSource1.Add(TextBox1.Text)
    End Sub
 
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        'Remove the selected item.
        BindingSource1.RemoveCurrent()
    End Sub
 
End Class

Note that there's not actually a need for code like this:

If My.Settings.ComboBox1Items Is Nothing Then
    ' Required only for first run.
    My.Settings.ComboBox1Items = New Specialized.StringCollection
End If

When you add a StringCollection to your settings, note that the Value field is empty by default. That's what causes the setting property to be Nothing by default. If you edit the Value and add an item, notice that the Value field is populated with an XML snippet, which actually creates a StringCollection object. If you then edit again and remove the item, the XML remains. That way, your setting property will contain an empty StringCollection object by default and you never have to test for Nothing.