単純な双方向ループチェーンテーブル

public class LinkedList<E> {

    int size = 0;
    Node<E> head = new Node<E>(null, null, null);

    public LinkedList() {
        head.next = head.previous = head;
    }

    public void add(E date) {
        //   
        Node<E> newNode = new Node<E>(head.previous, date, head);   // prev prev  next 
        newNode.previous.next = newNode;    // ， 
        newNode.next.previous = newNode;    // ， 
        size++;
    }

    public E get(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException("Index:" + index + ",size:" + size);
        }
        Node<E> node = head;
        if (index < (size >> 1)) {           
            for (int i = 0; i <= index; i++) {  //head ，i<=index index=0 ， head.next
                node = node.next;           // 
            }
        }else{
            for(int i=size;i>index;i--){
                node=node.previous;
            }
        }
        return node.getData();
    }

    public int size() {
        return size;
    }

    public static void main(String[] args) {
        LinkedList<Integer> list = new LinkedList<Integer>();
        list.add(1);
        list.add(2);
        list.add(3);
        list.add(4);
        list.add(5);
        list.add(6);
        list.add(7);
        list.add(8);
        System.out.println("list.get(3)="+list.get(3));
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
        }
    }


class Node<E> {

    E data;
    Node<E> next;
    Node<E> previous;

    public Node(Node<E> previous, E data, Node<E> next) {
        this.data = data;
        this.next = next;
        this.previous = previous;
    }
    public E getData(){
       return data;
    }

    public void setData(E data){
        this.data=data;
    }
 }


}