Anticlockwise spiral conversion of doubly linked list in vb.net

Vb program for Anticlockwise spiral conversion of doubly linked list. Here problem description and explanation.

' Include namespace system
Imports System 
'  Vb.net program for
'  Convert a doubly linked list anticlockwise spiral form

'  This is Linked List Node
Public Class LinkNode
    Public  data As Integer
    Public  [next] As LinkNode
    Public  prev As LinkNode
    Public Sub New(ByVal data As Integer)
        Me.data = data
        Me.next = Nothing
        Me.prev = Nothing
    End Sub
End Class
public Class DoublyLinkedList
    Public  head As LinkNode
    Public  tail As LinkNode
    Public Sub New()
        '  Set head and tail
        Me.head = Nothing
        Me.tail = Nothing
    End Sub
    '  Insert new node at end position
    Public Sub insert(ByVal value As Integer)
        '  Create a node
        Dim node As LinkNode = New LinkNode(value)
        if (Me.head  Is  Nothing) Then
            '  Add first node
            Me.head = node
            Me.tail = node
            Return
        End If
        '  Add node at last position
        Me.tail.[next] = node
        node.prev = Me.tail
        Me.tail = node
    End Sub
    '  Display node element of doubly linked list
    Public Sub display()
        if (Me.head  Is  Nothing) Then
            Console.WriteLine("Empty Linked List")
        Else
            Console.Write("Linked List Head to Tail :")
            '  Get first node of linked list
            Dim temp As LinkNode = Me.head
            '  iterate linked list
            while (temp IsNot Nothing)
                '  Display node value
                Console.Write("  " + temp.data.ToString())
                '  Visit to next node
                temp = temp.[next]
            End While
            Console.Write( vbLf &"Linked List Tail to Head :")
            '  Get last node of linked list
            temp = Me.tail
            '  iterate linked list
            while (temp IsNot Nothing)
                '  Display node value
                Console.Write("  " + temp.data.ToString())
                '  Visit to prev node
                temp = temp.prev
            End While
        End IF
    End Sub
    Public Sub spiralTransform()
        if (Me.head  Is  Nothing OrElse 
            Me.head.[next]  Is  Nothing) Then
            Return
        End If
        Dim last As LinkNode = Me.tail
        Dim current As LinkNode = Me.head
        Dim auxiliary As LinkNode = Nothing
        Dim temp As LinkNode = Nothing
        Dim back As LinkNode = Nothing
        '  Set new head
        Me.head = Me.tail
        while (current IsNot Nothing AndAlso last IsNot Nothing)
            if (current  Is  last) Then
                current.[next] = Nothing
                current.prev = back
                Me.tail = current
                '  Set new last node
                Return
            ElseIf (current.[next]  Is  last) Then
                current.[next] = Nothing
                current.prev = last
                last.[next] = current
                last.prev = back
                '  Set new last node
                Me.tail = current
                Return
            End If
            '  Swap link
            auxiliary = current.[next]
            temp = last.prev
            current.prev = last
            last.[next] = current
            current.[next] = temp
            last.prev = back
            back = current
            current = auxiliary
            last = temp
        End While
    End Sub
    Public Shared Sub Main(ByVal args As String())
        Dim dll As DoublyLinkedList = New DoublyLinkedList()
        '  Insert following linked list nodes
        dll.insert(1)
        dll.insert(2)
        dll.insert(3)
        dll.insert(4)
        dll.insert(5)
        dll.insert(6)
        dll.insert(7)
        dll.insert(8)
        dll.insert(9)
        Console.WriteLine( vbLf &"Before anticlockwise spiral conversion")
        '  Display all node
        dll.display()
        Console.WriteLine( vbLf &"After anticlockwise spiral conversion")
        dll.spiralTransform()
        dll.display()
    End Sub
End Class

Output

Before anticlockwise spiral conversion
Linked List Head to Tail :  1  2  3  4  5  6  7  8  9
Linked List Tail to Head :  9  8  7  6  5  4  3  2  1
After anticlockwise spiral conversion
Linked List Head to Tail :  9  1  8  2  7  3  6  4  5
Linked List Tail to Head :  5  4  6  3  7  2  8  1  9