简单模拟一个双向链表，用java实现

package com.gsh.test05;

/**
 * 节点类
 * @param <E>
 */
public class Node<E> {
    private Node<E> pre;
    private E element;
    private Node<E> next;

    public Node<E> getPre() {
        return pre;
    }

    public void setPre(Node<E> pre) {
        this.pre = pre;
    }

    public E getElement() {
        return element;
    }

    public void setElement(E e) {
        this.element = e;
    }

    public Node<E> getNext() {
        return this.next;
    }

    public void setNext(Node<E> next) {
        this.next = next;
    }

    @Override
    public String toString() {
        return "Node{" +
                "pre=" + pre +
                ", element=" + element +
                ", next=" + next +
                '}';
    }

}

package com.gsh.test05;

/**
 * 构建一个模拟的双向链表
 * @param <E>
 */

public class MyLinkedList<E> {
    private Node<E> headNode;
    private Node<E> tailNode;
    private int count = 0;

    public MyLinkedList() {
    }

    public void add(E e) {
        //将添加的元素封装位一个对象
        Node<E> n = new Node<>();
        n.setElement(e);

        if (headNode == null) {//如果是第一个节点
            n.setPre(null);
            //将当前头节点指向该节点
            headNode = n;
        } else {//非第一个节点
            n.setPre(tailNode);
            n.getPre().setNext(n);
        }

        n.setNext(null);
        //将当尾头节点指当前该节点
        tailNode = n;
        count++;
    }

    public int getSize(){
        return this.count;
    }

    public E getElement(int index){
        if(index<0||index>=count){
            throw new IndexOutOfBoundsException();
        }
        Node<E> n = headNode;
        for (int i = 0; i < index; i++) {
            n=n.getNext();
        }
        return n.getElement();
    }
    public static void main(String[] args) {
        MyLinkedList<String> intList = new MyLinkedList<>();
        intList.add("aa");
        intList.add("bb");
        intList.add("cc");
        intList.add("dd");
        intList.add("ee");
        intList.add("ff");
        String s = intList.getElement(6);
        System.out.println(s);
    }
}