双向链表

<pre name="code" class="java">public class DoubleList<T> {private Node<T> head = null;private Node<T> tail = null;private int length = 0;public static void main(String[] args) {DoubleList<Integer> dl = new DoubleList<Integer>();System.out.println("是否为空："+dl.isEmpty());dl.addToHead(2);dl.addToHead(5);dl.addToHead(9);dl.addToTail(10);System.out.print("链表为：");dl.printList();dl.insertIndexAfter(2, 7);System.out.print("在第2个数后插入7后链表为为：");dl.printList();dl.insertIndexBefore(3, 13);System.out.print("在第3个数前插入13后链表为为：");dl.printList();dl.removeByKey(7);System.out.print("移除键值7后的链表为：");dl.printList();dl.removeByIndex(3);System.out.print("移除第3个数后的链表为：");dl.printList();dl.deleteFromHead();System.out.print("删除头部节点后的链表为：");dl.printList();dl.deleteFromTail();System.out.print("删除尾部节点后的链表为：");dl.printList();dl.updateKeyByIndex(1, 3);System.out.print("将第1个数更新为3后的链表为：");dl.printList();System.out.println("第2个节点为："+dl.getKeyByIndex(2));System.out.println("是否为空："+dl.isEmpty());System.out.println("是否包含5："+dl.isContains(5));System.out.println("链表长度为："+dl.getSize());System.out.println("头结点为："+dl.getHeadKey());System.out.println("尾结点为："+dl.getTailKey());dl.clearList();System.out.print("清空后的链表为：");dl.printList();}//构建一个空链表public DoubleList() {head = null;tail = null;length = 0;}//构建一个节点的链表public DoubleList(T data) {head  = new Node<T>(data);tail = head;length = 1;}//把一个节点插入到链表前面private void addToHead(T key) {if(head != null) {Node<T> nd = new Node<T>(key);nd.next = head;head.prev = nd;head = nd;} else {head = new Node<T>(key);tail = head;}length++;}//把一个节点插入到链表后面private void addToTail(T key) {if(tail != null) {Node<T> nd = new Node<T>(key);tail.next = nd;nd.prev = tail;tail = nd;} else {tail = new Node<T>(key);head = tail;}length++;}//在索引index前插入值private boolean insertIndexBefore(int index,T insertvalue) {if(index<1 || index>length) {System.err.println("索引越界");return false;}Node<T> insertNode = new Node<T>(insertvalue);Node<T> nd = head;int j=0;while(nd != null) {j++;if(j == index) {if(nd.prev == null) {addToHead(insertvalue);} else {nd.prev.next = insertNode;insertNode.prev = nd.prev;insertNode.next = nd;nd.prev = insertNode;length++;}return true;}nd=nd.next;}return false;}//在索引index后插入值private boolean insertIndexAfter(int index,T insertvalue) {if(index<1 || index>length) {System.err.println("索引越界");return false;}Node<T> insertNode = new Node<T>(insertvalue);Node<T> nd = head;int j=0;while(nd != null) {j++;if(j == index) {if(nd.next == null) {addToTail(insertvalue);} else {nd.next.prev = insertNode;insertNode.next = nd.next;nd.next = insertNode;insertNode.prev = nd;length++;}return true;}nd=nd.next;}return false;}//移除第一个键值为key的节点private boolean removeByKey(T key) {Node<T> nd = head;while(nd != null) {if(key == nd.key) {if(nd.prev == null){return deleteFromHead();}else if(nd.next == null) {return deleteFromTail();}else {nd.prev.next = nd.next;nd.next.prev = nd.prev;length--;}return true;}nd = nd.next;}return false;}//移除索引为i的值private boolean removeByIndex(int index) {if(index<1 || index>length) {System.err.println("索引越界");return false;}Node<T> nd = head;int j=0;while(nd != null) {j++;if(j == index) {if(nd.prev == null){return deleteFromHead();}else if(nd.next == null) {return deleteFromTail();}else {nd.prev.next = nd.next;nd.next.prev = nd.prev;length--;}return true;}nd=nd.next;}return false;}//删除尾部节点private boolean deleteFromTail() {if(tail == null) {return false;}else {tail.prev.next = null;tail = tail.prev;length--;return true;}}//删除头部节点private boolean deleteFromHead() {if(head == null) {return false;}else {head.next.prev = null;head = head.next;length--;return true;}}private boolean updateKeyByIndex(int i,T key) {if(i<1 || i>length) {System.err.println("索引越界");return false;}Node<T> nd = head;for(int j=i-1;j>0;j--) {nd = nd.next;}nd.key = key;return true;}//获得第i个键值private T getKeyByIndex(int i) {if(i<1 || i>length) {System.err.println("索引越界");return null;}Node<T> nd = head;for(int j=i-1;j>0;j--) {nd = nd.next;}return nd.key;}private boolean isEmpty() {return length == 0;}private boolean isContains(T key) {Node<T> nd = head;while(nd != null) {if(nd.key == key) {return true;}nd = nd.next;}return false;}private int getSize() {return length;}private T getHeadKey() {return head.key;}private T getTailKey() {return tail.key;}private void printList() {if(isEmpty()) {System.out.println("是空链表");} else {Node<T> temp = head;while(temp != null) {System.out.print(temp.key+" ");temp = temp.next;}}System.out.println();}private void clearList() {head = null;tail = null;length = 0;}private static class Node<T> {Node<T> prev = null;Node<T> next = null;T key = null;public Node(T key) {this.key = key;}}}

运行结果为：

是否为空：true链表为：9 5 2 10 在第2个数后插入7后链表为为：9 5 7 2 10 在第3个数前插入13后链表为为：9 5 13 7 2 10 移除键值7后的链表为：9 5 13 2 10 移除第3个数后的链表为：9 5 2 10 删除头部节点后的链表为：5 2 10 删除尾部节点后的链表为：5 2 将第1个数更新为3后的链表为：3 2 第2个节点为：2是否为空：false是否包含5：false链表长度为：2头结点为：3尾结点为：2清空后的链表为：是空链表