Java实现无头双向链表操作
作者:Sasura_321
这篇文章主要为大家详细介绍了Java实现无头双向链表的基本操作,文中示例代码介绍的非常详细,具有一定的参考价值,感兴趣的小伙伴们可以参考一下
本文实例为大家分享了Java实现无头双向链表的具体代码,供大家参考,具体内容如下
无头双向链表的结构:
代码分析
节点结构
class Node { private int data; private Node next; private Node prev; public Node(int data) { this.data = data; this.prev = null; this.next = null; } } private Node head; // 头节点 private Node last; // 尾节点 public DoubleLinked() { this.head = null; this.last = null; }
1. 头插法
/** * 1.头插法 * @param data */ public void addFirst(int data) { Node node = new Node(data); if (this.head == null) { this.head = node; this.last = node; } else { node.next = this.head; this.head.prev = node; this.head = node; } }
先判断链表是否为空,若为空,则直接插入,头节点和尾节点都直接指向新插入的元素;
若链表不为空,则把要插入节点的 next 指向链表头节点,头节点的 prev 指向新插入的节点,最后更新头节点为新插入节点,插入过程如下图所示:
2. 尾插法
/** * 2.尾插法 * @param data */ public void addLast(int data) { Node node = new Node(data); if (this.head == null) { this.head = node; this.last = node; } else { this.last.next = node; node.prev = this.last; this.last = node; } }
若链表为空,同头插法;
若链表不为空,则把链表尾节点的 next 指向要插入节点,要插入节点的 prev 指向链表尾节点,最后更新尾节点为新插入节点,插入过程如下图所示:
3. 查找是否包含关键字 key 在单链表中
// 查找 private Node searchIndex(int index) { checkIndex(index); int count = 0; Node cur = this.head; while (count != index) { cur = cur.next; count++; } return cur; } // 合法性检查 private void checkIndex(int index) { if (index < 0 || index > getLength()) { throw new IndexOutOfBoundsException("下标不合法!"); } } /** * 3.任意位置插入,第一个数据节点为0号下标 * @param index 插入位置 * @param data 插入的值 * @return true/false */ @Override public boolean addIndex(int index, int data) { if (index ==0) { addFirst(data); return true; } if (index == getLength()) { addLast(data); return true; } // cur 指向index位置的节点 Node cur = searchIndex(index); Node node = new Node(data); node.next = cur; cur.prev.next = node; node.prev = cur.prev; cur.prev = node; return true; }
4. 查找是否包含关键字 key 在单链表中
/** * 4.查找是否包含关键字 key 在单链表中 * @param key 要查找的关键字 * @return true/false */ @Override public boolean contains(int key) { Node cur = this.head; while (cur != null) { if (cur.data == key) { return true; } cur = cur.next; } return false; }
5. 删除第一次出现关键字为 key 的节点
/** * 5.删除第一次出现关键字为 key 的节点 * @param key * @return */ @Override public int remove(int key) { Node cur = this.head; int oldData = 0; while (cur != null) { if (cur.data == key) { oldData = cur.data; // 头节点 if (cur == this.head) { this.head = this.head.next; this.head.prev = null; } else { // cur.next != null --->不是尾节点 if (cur.next != null) { cur.next.prev = cur.prev; } else { this.last = cur.prev; } } return oldData; } cur = cur.next; } return -1; }
6. 删除所有值为 key 的节点
/** * 6.删除所有值为 key 的节点 * @param key */ @Override public void removeAllKey(int key) { Node cur = this.head; while (cur != null) { if (cur.data == key) { // 头节点 if (cur == this.head) { this.head = this.head.next; this.head.prev = null; } else { cur.prev.next = cur.next; // cur.next != null --->不是尾节点 if (cur.next != null) { cur.next.prev = cur.prev; } else { this.last = cur.prev; } } } cur = cur.next; } }
7. 得到单链表的长度
/** * 7.得到单链表的长度 * @return */ @Override public int getLength() { int count = 0; Node cur = this.head; while (cur != null) { count++; cur = cur.next; } return count; }
8. 打印链表
/** * 8.打印链表 */ @Override public void display() { if (this.head == null) { return ; } Node cur = this.head; while (cur != null) { System.out.print(cur.data + " "); cur = cur.next; } System.out.println(); }
9. 清空顺序表以防内存泄漏
/** * 9.清空顺序表以防内存泄漏 */ @Override public void clear() { while(this.head != null) { Node cur = this.head.next; this.head.next = null; this.head.prev = null; this.head = cur; } }
接口、实现方法、测试
1. 接口
package com.github.doubly; // 不带头节点单链表的实现 public interface IDoubleLinked { // 1.头插法 void addFirst(int data); // 2.尾插法 void addLast(int data); // 3.任意位置插入,第一个数据节点为0号下标 boolean addIndex(int index, int data); // 4.查找是否包含关键字 key 在单链表中 boolean contains(int key); // 5.删除第一次出现关键字为 key 的节点 int remove(int key); // 6.删除所有值为 key 的节点 void removeAllKey(int key); // 7.得到单链表的长度 int getLength(); // 8.打印链表 void display(); // 9.清空顺序表以防内存泄漏 void clear(); }
2. 实现方法
package com.github.doubly; public class DoubleLinked implements IDoubleLinked { class Node { private int data; private Node next; private Node prev; public Node(int data) { this.data = data; this.prev = null; this.next = null; } } private Node head; // 头节点 private Node last; // 尾节点 public DoubleLinked() { this.head = null; this.last = null; } /** * 1.头插法 * @param data */ @Override public void addFirst(int data) { Node node = new Node(data); if (this.head == null) { this.head = node; this.last = node; } else { node.next = this.head; this.head.prev = node; this.head = node; } } /** * 2.尾插法 * @param data */ @Override public void addLast(int data) { Node node = new Node(data); if (this.head == null) { this.head = node; this.last = node; } else { this.last.next = node; node.prev = this.last; this.last = node; } } // 查找 private Node searchIndex(int index) { checkIndex(index); int count = 0; Node cur = this.head; while (count != index) { cur = cur.next; count++; } return cur; } // 合法性检查 private void checkIndex(int index) { if (index < 0 || index > getLength()) { throw new IndexOutOfBoundsException("下标不合法!"); } } /** * 3.任意位置插入,第一个数据节点为0号下标 * @param index 插入位置 * @param data 插入的值 * @return true/false */ @Override public boolean addIndex(int index, int data) { if (index ==0) { addFirst(data); return true; } if (index == getLength()) { addLast(data); return true; } // cur 指向index位置的节点 Node cur = searchIndex(index); Node node = new Node(data); node.next = cur; cur.prev.next = node; node.prev = cur.prev; cur.prev = node; return true; } /** * 4.查找是否包含关键字 key 在单链表中 * @param key 要查找的关键字 * @return true/false */ @Override public boolean contains(int key) { Node cur = this.head; while (cur != null) { if (cur.data == key) { return true; } cur = cur.next; } return false; } /** * 5.删除第一次出现关键字为 key 的节点 * @param key * @return */ @Override public int remove(int key) { Node cur = this.head; int oldData = 0; while (cur != null) { if (cur.data == key) { oldData = cur.data; // 头节点 if (cur == this.head) { this.head = this.head.next; this.head.prev = null; } else { // cur.next != null --->不是尾节点 if (cur.next != null) { cur.next.prev = cur.prev; } else { this.last = cur.prev; } } return oldData; } cur = cur.next; } return -1; } /** * 6.删除所有值为 key 的节点 * @param key */ @Override public void removeAllKey(int key) { Node cur = this.head; while (cur != null) { if (cur.data == key) { // 头节点 if (cur == this.head) { this.head = this.head.next; this.head.prev = null; } else { cur.prev.next = cur.next; // cur.next != null --->不是尾节点 if (cur.next != null) { cur.next.prev = cur.prev; } else { this.last = cur.prev; } } } cur = cur.next; } } /** * 7.得到单链表的长度 * @return */ @Override public int getLength() { int count = 0; Node cur = this.head; while (cur != null) { count++; cur = cur.next; } return count; } /** * 8.打印链表 */ @Override public void display() { if (this.head == null) { return ; } Node cur = this.head; while (cur != null) { System.out.print(cur.data + " "); cur = cur.next; } System.out.println(); } /** * 9.清空顺序表以防内存泄漏 */ @Override public void clear() { while(this.head != null) { Node cur = this.head.next; this.head.next = null; this.head.prev = null; this.head = cur; } } }
3. 测试
package com.github.doubly; public class TestDemo { public static void main(String[] args) { DoubleLinked doubleLinked = new DoubleLinked(); doubleLinked.addFirst(10); doubleLinked.addFirst(20); doubleLinked.addFirst(30); doubleLinked.addFirst(40); doubleLinked.addFirst(50); doubleLinked.display(); doubleLinked.addIndex(0,100); doubleLinked.addIndex(1,200); doubleLinked.addIndex(0,300); doubleLinked.addLast(40); doubleLinked.addLast(50); doubleLinked.display(); doubleLinked.remove(300); doubleLinked.display(); doubleLinked.removeAllKey(50); doubleLinked.display(); } }
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持脚本之家。