Java实现无头双向链表
本文共 9166 字，大约阅读时间需要 30 分钟。
创建空的成员变量并用构造函数初始化
class ListNode { public int data; public ListNode next;//节点引用 public ListNode prev;//节点前驱 public ListNode(int data) { this.data = data; }} 头节点和尾结点
public class DoubleLinkedList { public ListNode head; public ListNode tail; 头插法
//头插法 public void addFirst(int data) { ListNode node = new ListNode(data); if (this.head == null) { this.head = node; this.tail = node; } else { node.next = this.head; this.head.prev = node; this.head = node; } } 
头插法的过程如代码和图所示，分为如果链表还没有头节点和以及有头节点，插入顺序不再赘述。
尾插法
//尾插法 public void addLast(int data) { ListNode node = new ListNode(data); if (this.head == null) { this.tail = node; this.head = node; } else { this.tail.next = node; node.prev = this.tail; this.tail = node; } } 
打印链表
//打印链表 public void display() { ListNode cur = this.head; while (cur != null) { System.out.print(cur.data + " "); cur = cur.next; } System.out.println(); } 任意位置插入，第一个数据节点为0的下标
计算链表长度
//任意位置插入，第一个数据节点为0的下标 public void addIndex (int index,int data) { if (index < 0 || index > size()) { return; } if (index == 0) { addFirst(data); return; } if (index == size()) { addLast(data); return; } ListNode cur = searchIndex(index); ListNode node = new ListNode(data); node.next = cur; node.prev = cur.prev; cur.prev.next = node; cur.prev = node; } public ListNode searchIndex(int index) { ListNode cur = this.head; while (index > 0) { cur = cur.next; index --; } return cur; } //求链表长度 public int size() { ListNode cur = this.head; int count = 0; while (cur != null) { cur = cur.next; count++; } return count; } 
删除第一次出现关键字为key的点
//删除第一次出现关键字为key的点 public void remove(int key) { ListNode cur = this.head; while (cur != null) { if (cur.data == key) { //删除的是否为头节点 if (cur == this.head) { this.head = this.head.next; this.head.prev = null; } else { cur.prev.next = cur.next; if (cur.next != null) { //删除的不是尾结点 cur.next.prev = cur.prev; } else { this.tail = cur.prev; } } //删除完成 return; } else { cur = cur.next; } } } 删除所有key节点
public void removeAllkey (int key) { ListNode cur = this.head; while (cur != null) { if (cur.data == key) { //删除的是否为头节点 if (cur == this.head) { this.head = this.head.next; this.head.prev = null; } else { cur.prev.next = cur.next; if (cur.next != null) { //删除的不是尾结点 cur.next.prev = cur.prev; } else { this.tail = cur.prev; } } } cur = cur.next; } } 清空链表
//清空回收链表 public void clear() { ListNode cur = this.head; ListNode curNext; while (cur != null) { curNext = cur.next; cur.next = null; cur.prev = null; cur = curNext; } this.head = null; this.tail = null; } 查找是否含有关键字key
//查找是否包含关键字key public boolean contains (int key) { if (head == null) { return false; } ListNode cur = this.head; while (cur != null) { if (cur.data == key) { return true; } cur = cur.next; } return false; }} 测试代码
public class Test { public static void main(String[] args) { DoubleLinkedList doubleLinkedList = new DoubleLinkedList(); doubleLinkedList.addFirst(3); doubleLinkedList.addFirst(3); doubleLinkedList.addFirst(3); doubleLinkedList.addLast(4); doubleLinkedList.addLast(5); doubleLinkedList.addLast(3); //3 2 1 4 5 6 doubleLinkedList.display(); doubleLinkedList.addIndex(3,999); //3 2 1 999 4 5 6 doubleLinkedList.display(); doubleLinkedList.remove(5); doubleLinkedList.display(); System.out.println(doubleLinkedList.contains(9)); doubleLinkedList.removeAllkey(3); doubleLinkedList.display(); doubleLinkedList.clear(); System.out.println("dadedsffw"); }} 完整代码
import java.util.List;/** * @Author 袁媛 * @Date 2020/7/31 * @Time 10:54 */class ListNode { public int data; public ListNode next; public ListNode prev; public ListNode(int data) { this.data = data; }}public class DoubleLinkedList { public ListNode head; public ListNode tail; //头插法 public void addFirst(int data) { ListNode node = new ListNode(data); if (this.head == null) { this.head = node; this.tail = node; } else { node.next = this.head; this.head.prev = node; this.head = node; } } //尾插法 public void addLast(int data) { ListNode node = new ListNode(data); if (this.head == null) { this.tail = node; this.head = node; } else { this.tail.next = node; node.prev = this.tail; this.tail = node; } } //打印链表 public void display() { ListNode cur = this.head; while (cur != null) { System.out.print(cur.data + " "); cur = cur.next; } System.out.println(); } //任意位置插入，第一个数据节点为0的下标 public void addIndex (int index,int data) { if (index < 0 || index > size()) { return; } if (index == 0) { addFirst(data); return; } if (index == size()) { addLast(data); return; } ListNode cur = searchIndex(index); ListNode node = new ListNode(data); node.next = cur; node.prev = cur.prev; cur.prev.next = node; cur.prev = node; } public ListNode searchIndex(int index) { ListNode cur = this.head; while (index > 0) { cur = cur.next; index --; } return cur; } //求链表长度 public int size() { ListNode cur = this.head; int count = 0; while (cur != null) { cur = cur.next; count++; } return count; } //删除第一次出现关键字为key的点 public void remove(int key) { ListNode cur = this.head; while (cur != null) { if (cur.data == key) { //删除的是否为头节点 if (cur == this.head) { this.head = this.head.next; this.head.prev = null; } else { cur.prev.next = cur.next; if (cur.next != null) { //删除的不是尾结点 cur.next.prev = cur.prev; } else { this.tail = cur.prev; } } //删除完成 return; } else { cur = cur.next; } } } //删除所有key节点 public void removeAllkey (int key) { ListNode cur = this.head; while (cur != null) { if (cur.data == key) { //删除的是否为头节点 if (cur == this.head) { this.head = this.head.next; this.head.prev = null; } else { cur.prev.next = cur.next; if (cur.next != null) { //删除的不是尾结点 cur.next.prev = cur.prev; } else { this.tail = cur.prev; } } } cur = cur.next; } } //清空回收链表 public void clear() { ListNode cur = this.head; ListNode curNext; while (cur != null) { curNext = cur.next; cur.next = null; cur.prev = null; cur = curNext; } this.head = null; this.tail = null; } //查找是否包含关键字key public boolean contains (int key) { if (head == null) { return false; } ListNode cur = this.head; while (cur != null) { if (cur.data == key) { return true; } cur = cur.next; } return false; }} 转载地址：http://coanz.baihongyu.com/
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