Try this :
Setting:
Dim number As Integer
Dim num As String
Dim al As New ArrayList()
If Not (al.Contains(number)) Then
al.Add(number)
End If
Getting:
For Each number In al
num = number.ToString()
Next
Reference:
https://stackoverflow.com/questions/6185149/vb-net-how-to-remove-duplicates-from-an-array