一个LinkedList的实现，非java util 的实现，没有用java util容器，纯实现过程，主要看算法。

/*   * To change this template, choose Tools | Templates   * and open the template in the editor.   */  package linkedlisttest;    /**   *   * @author Lindily   */  public class LinkedList<E> {        int size = 0;      Node<E> head = new Node(null, null, null);        public LinkedList() {          head.next = head.previous = head;      }        public void add(E node) {          //核心 循环双向链表          Node<E> newNode = new Node(head.previous, node, head);   //新节点的prev指向头结点的prev 新节点的next指向头结点          newNode.previous.next = newNode;    //调整，新节点的前一个的后一个          newNode.next.previous = newNode;    //调整，新节点的后一个的前一个          size++;      }        public Node get(int index) {          if (index < 0 || index >= size) {              throw new IndexOutOfBoundsException("Index:" + index + ",size:" + size);          }          Node node = head;          if (index < (size >> 1)) {          //index转为二进制带符号向右移动一个bit，相当于index/2              for (int i = 0; i <= index; i++) {  //head是哑元，i<=index当index=0时，返回head.next                  node = node.next;           //对头结点进行迭代              }          }else{              for(int i=size;i>index;i--){                  node=node.previous;              }          }          return node;      }        public int size() {          return size;      }        public static void main(String[] args) {          LinkedList list = new LinkedList();          list.add(1);          list.add(2);          list.add(3);          for (int i = 0; i < list.size; i++) {              System.out.println(list.get(i).node);          }      }  }    class Node<E> {        E node;      Node<E> next;      Node<E> previous;        public Node(Node<E> previous, E node, Node<E> next) {          this.node = node;          this.next = next;          this.previous = previous;      }  }

/*   * To change this template, choose Tools | Templates   * and open the template in the editor.   */  package linkedlisttest;    /**   *   * @author Lindily   */  public class SingleLinkedList<T> {        int size = 0;      Node<T> head, tail;        public SingleLinkedList() {          head = tail = null;      }        public void add(T node) {          if (size == 0) {              head = tail = new Node<T>(node, null);          } else {              tail.next = new Node<T>(node, null);              tail = tail.next;          }          size++;      }        public Node<T> get(int index) {          if (index < 0 || index >= size) {              throw new IndexOutOfBoundsException("Index:" + index + ",size:" + size);          }          Node<T> node = head;          for (int i = 0; i < index; i++) {  //当index=0时，i不小于index(零不小于零)，于是直接return头结点，与linkedList不同，head不是哑元              node = node.next;           //对头结点进行迭代          }          return node;      }        public int size(){          return size;      }        public static void main(String[] args){          SingleLinkedList list=new SingleLinkedList();          list.add(1);          list.add(2);          list.add(3);          for(int i=0;i<list.size();i++){              System.out.println(list.get(i).node);          }      }  }    class Node<T> {        T node;      Node<T> next;        public Node(T node, Node next) {          this.node = node;          this.next = next;      }  }