双链表代码记录

双向链表：无序添加、有序添加、遍历、反转

package com.example.notes.linkedlist;

import lombok.Data;



public class DoublelinkedListDemo {
    public static void main(String[] args) {
        HeroNode2 heroNode1 = new HeroNode2(1, "宋江", "及时雨");
        HeroNode2 heroNode2 = new HeroNode2(2, "卢俊义", "玉麒麟");
        HeroNode2 heroNode3 = new HeroNode2(3, "吴勇", "智多星");
        HeroNode2 heroNode4 = new HeroNode2(4, "林冲", "豹子头");

        SinglelinkedList2 singlelinkedList = new SinglelinkedList2();
        singlelinkedList.addByOrder(heroNode4);
        singlelinkedList.addByOrder(heroNode1);
        singlelinkedList.addByOrder(heroNode3);
        singlelinkedList.addByOrder(heroNode2);
        singlelinkedList.list();
        System.out.println("-------------------------------------------------");
        singlelinkedList.reversetList(singlelinkedList.getHead());
        singlelinkedList.list();
        System.out.println("-------------------------------------------------");
    }

}

//定义
@Data
class SinglelinkedList2 {
    //初始化头结点
    private HeroNode2 head = new HeroNode2(0, "", "");

    
    public void add(HeroNode2 heroNode) {
        //因为head节点不能动，需要一个辅助遍历temp
        HeroNode2 temp = head;
        while (true) {
            //找到链表最后
            if (temp.next == null) {
                break;
            }
            //如果不是最后则后移
            temp = temp.next;
        }
        temp.next = heroNode;
        heroNode.pre = temp;
    }

    
    public void addByOrder(HeroNode2 heroNode) {
        //因为head节点不能动，需要一个辅助遍历temp
        HeroNode2 temp = head;
        boolean exist = false;
        boolean end = false;
        while (true) {
            //找到链表最后
            if (temp.next == null) {        //当前为temp链表最后
                end = true;
                break;
            }
            if (temp.next.no > heroNode.no) {        //找到位置
                break;
            } else if (temp.no == heroNode.no) {
                exist = true;
                break;
            }
            //如果不是正确位置则后移
            temp = temp.next;
        }
        if (exist) {
            System.out.println("数据已存在！");
        } else {
            heroNode.pre = temp;
            heroNode.next = temp.next;
            if (!end) {
                temp.next.pre = heroNode;
            }
            temp.next = heroNode;

        }
    }

    public void list() {
        if (head.next == null) {
            System.out.println("链表为空！");
        }
        HeroNode2 temp = head.next;
        while (true) {
            if (temp == null) {
                break;
            }
            System.out.print(temp.getPre());
            System.out.print(temp);
            System.out.println(temp.getNext());
            temp = temp.next;
        }
    }

    
    public static void reversetList(HeroNode2 heroNode) {
        //空链表或只有一个数据的链表，无需反转直接返回
        if (heroNode.next == null && heroNode.next.next == null) {
            return;
        }
        //定义辅助变量
        HeroNode2 cur = heroNode.next;        //当前节点，遍历原先链表
        HeroNode2 next = null;        //当前节点的下一个节点
        HeroNode2 temp = null;        //当前节点的下一个节点
        HeroNode2 reversetHead = new HeroNode2(0, "", "");
        while (cur != null) {
            boolean end = false;
            end = reversetHead.next == null;

            next = cur.next;
            cur.next = reversetHead.next;
            reversetHead.next = cur;
            cur.pre = reversetHead;
            if (!end) {
                cur.next.pre = cur;
            }
            cur = next;
        }
        heroNode.next = reversetHead;
    }

}

//定义节点
class HeroNode2 {
    public int no;
    public String name;
    public String nickname;
    public HeroNode2 pre;
    public HeroNode2 next;

    public HeroNode2(int no, String name, String nickname) {
        this.no = no;
        this.name = name;
        this.nickname = nickname;
    }

    public HeroNode2 getPre() {
        return pre;
    }

    public HeroNode2 getNext() {
        return next;
    }

    //为了显示方便
    @Override
    public String toString() {
        return "heroNode{" +
                "no=" + no +
                ", name='" + name + ''' +
                ", nickname='" + nickname +
                '}';
    }
}