Change the position of array item in vb.net

Public Shared Sub ChangeItemPos(ByVal a As Array)
    If (a IsNot Nothing) AndAlso (a.Length > 1) AndAlso (a.Rank = 1) Then
        Dim list As New ArrayList(a)
        Dim firstItem As Object = list.Item(0)
        list.RemoveAt(0)
        For index As Integer = 1 To list.Count - 1 Step 2
            ' Swap the items
            Dim temp As Object = list.Item(index)
            list.Item(index) = list.Item(index - 1)
            list.Item(index - 1) = temp
        Next
        list.Add(firstItem) ' Put firstItem into last
        list.CopyTo(a)
    End If
End Sub

Dim a As Integer() = {1, 2, 3, 4}
ChangeItemPos(a)