ArrayListJoin - Merging two ArrayList objects

' A reusable function that merges two ArrayList objects
' Example:
'     Dim al As New ArrayList()
'     al.Add("Jack")
'     al.Add("Mary")
'     val.Add("Bob")
'     al.Add("Tom")
'     
'     Dim al2 As New ArrayList()
'     al2.Add("Frank")
'     al2.Add("Lee")
'     al2.Add("Nick")
'     
'     al = ArrayListJoin(al, al2)

Function ArrayListJoin(ByVal al1 As ArrayList, ByVal al2 As ArrayList) As _
    ArrayList
    ' Note how we avoid time-consuming reallocations.
    ArrayListJoin = New ArrayList(al1.Count + al2.Count)
    ' Append the items in the two ArrayList arguments.
    ArrayListJoin.AddRange(al1)
    ArrayListJoin.AddRange(al2)
End Function


' Note: this code is taken from Francesco Balena's "Programming Microsoft 
' Visual Basic .NET" book (MS Press 2002)