Excel - VBA Removing Duplicates from Comboboxes - excel

Question

I am trying to create a subroutine to delete duplicates out of comboboxes. I input a number in place of X when I called the subroutine. I keep getting an error that tells me "Object Required" when i get to the subroutine. I know that means that something is not being properly initialized, but I cannot figure out how to fix my issue. Any help would be greatly appreciated. Thank you.
Private Sub UserForm_Initialize()
'ComboBox Populate
Dim rngNext As Range
Dim myRange As Range
Dim C As Integer
With Sheets("KEY")
Set rngNext = .Range("B500").End(xlUp).Offset(1, 0)
End With
rngNext.Select
Set myRange = Range("B2", rngNext)
With ComboBox1
For Each rngNext In myRange
If rngNext <> "" Then .AddItem rngNext
Next rngNext
End With
Call RemoveDuplicates(1)
End sub
Private Sub RemoveDuplicates(X)
'Remove Duplicates
Dim i As Long
Dim j As Long
With "ComboBox" & X
For i = 0 To .ListCount + 1 'Getting object required error in this line
For j = .ListCount To (i + 1) Step -1
If .List(j) = .List(i) Then
.RemoveItem j
End If
Next
Next
End With
End Sub
Final Code
Everything works great for removing duplicates.
Public allCBoxes As Collection
Private Sub UserForm_Initialize()
Set allCBoxes = New Collection
allCBoxes.Add ComboBox1
'ComboBox Populate
Dim rngNext As Range
Dim myRange As Range
Dim C As Integer
With Sheets("KEY")
Set rngNext = .Range("B500").End(xlUp).Offset(1, 0)
End With
rngNext.Select
Set myRange = Range("B2", rngNext)
With ComboBox1
For Each rngNext In myRange
If rngNext <> "" Then .AddItem rngNext
Next rngNext
End With
Call RemoveDuplicates(1)
End sub
Private Sub RemoveDuplicates(X)
'Remove Duplicates
Dim i As Long
Dim j As Long
With allCBoxes(X)
For i = 0 To .ListCount + 1
For j = .ListCount -1 To (i + 1) Step -1
If .List(j) = .List(i) Then
.RemoveItem j
End If
Next
Next
End With
End Sub

Answer 1

You get an error because you're passing a string, not an object.
Although intuitively you can think that:
"ComboBox" & X
will become, for example if x = 5,
ComboBox5
you're wrong because you're actually building a string:
"ComboBox5"
And, clearly, if you call a method of a ComboBox object on a String, you will be prompted of "Object Required".
What you want to do is impossible in VBA, where you cannot define variable names at run-time (i.e. ComboBox & X, even if not "as string", will not reference the variable ComboBox5). To reach what you want, I suggest to create a public collection:
Dim allCBoxes As Collection
then to populate it on the main procedure:
Set allCBoxes = New Collection
allCBoxes.Add ComboBox1
allCboxes.Add ComboBox2
'etc.
and finally recovering the "Xth" combobox like this:
With allCBoxes(X)
End With

Answer 2

If you want to reference a control using its string name, use the Controls function.
Such as:
With Controls("Combobox" & X)
Does that resolve the problem?

Answer 3

As mentioned in my comment above, here's a different approach towards solving the underlying problem: needing a combobox without duplicate values. This method uses a Dictionary object.
Let me know if you can adapt it to your needs, and if it works.
Private Sub UserForm_Initialize()
Dim oDictionary As Object
Dim strCellContent As String
Dim rngComboValues As Range
Dim rngCell As Range
Set rngComboValues = Range("A1:A26")
Set oDictionary = CreateObject("Scripting.Dictionary")
For Each rngCell In rngComboValues
strCellContent = rngCell.Value
If Not oDictionary.exists(strCellContent) Then
oDictionary.Add strCellContent, 0
End If
Next rngCell
For Each itm In oDictionary.keys
Me.ComboBox1.AddItem itm
Next itm
Set oDictionary = Nothing
End Sub