java双向链表的实现（部分功能）

 public class DoubleLinkedList {private Node head;private Node tail;private int size;public DoubleLinkedList() {head = new Node();tail = head;size = 0;}private class Node {public Object data;public Node next;public Node front;Node() {this.data = null;}Node(Object data) {this.data = data;}}//在链表指定的位置插入指定的元素,后插。index从0 到 size ,为0时加在head的后面public void add(int index, Object element) {if(index > size || index < 0) {throw new IndexOutOfBoundsException("index:" + index);}Node newNode = new Node(element);Node p = head;for(int i=0; i<index; i++) {p = p.next;}if(p.next != null){//若p不为最后一个节点newNode.front = p;newNode.next = p.next;p.next.front = newNode;p.next = newNode;}else{ //若p为最后一个节点p.next = newNode;newNode.front = p.front;tail = newNode;}size ++;}//在链表的最后加入指定的元素public void add(Object element) {add(size, element);}//获取指定位置的元素public Object get(int index) {if(index >size || index<0) {throw new IndexOutOfBoundsException("index:" + index);}Node p = head;int i = 0;while(p != tail) {p = p.next;if(i == index) {return p.data;}i++;}return null;}//清空列表public void clear() {head = null;tail = null;size = 0;}public static void main(String[] args) {DoubleLinkedList list = new DoubleLinkedList();for(int i=0; i<10; i++) {list.add(i);}for(int i=0; i<list.size; i++) {System.out.print(list.get(i) + " ");}}}