double linked list java

1class doublelinkedlist{  
2    Node head;
3    Node tail;
4
5    static class Node{
6        int data;
7        Node previous;
8        Node next;
9
10        Node(int data) { this.data = data; }
11    }
12
13    public void addLink(int data) {
14        Node node = new Node(data);
15
16        if(head == null) {
17            head = tail = node;
18            head.previous = null;
19        } else {
20            tail.next = node;
21            node.previous = tail;
22            tail = node;
23        }
24        tail.next = null;
25    }
26}