[数据结构与算法]双向链表实现Java 2021.12.22

package DataStructures.linkedList;

public class DoubleLinkedListDemo {

    public static void main(String[] args) {

        System.out.println("双向链表的测试：");

        HeroNode2 hero1 = new HeroNode2(1,"宋江","及时雨");
        HeroNode2 hero2 = new HeroNode2(2,"卢俊义","玉麒麟");
        HeroNode2 hero3 = new HeroNode2(3,"吴用","智多星");
        HeroNode2 hero4 = new HeroNode2(4,"林冲","豹子头");

        DoubleLinkedList doubleLinkedList = new DoubleLinkedList();
        doubleLinkedList.add(hero1);
        doubleLinkedList.add(hero2);

        doubleLinkedList.add(hero4);

        doubleLinkedList.list();

//        //修改
//        HeroNode2 newHeroNode = new HeroNode2(4,"linchong","baozitou");
//        doubleLinkedList.update(newHeroNode);
//        doubleLinkedList.list();
//
//        //删除
//        doubleLinkedList.delete(4);
//        doubleLinkedList.delete(1);
//        doubleLinkedList.delete(1);
//        doubleLinkedList.list();
        System.out.println("按顺序添加：");
        doubleLinkedList.addByOrder(hero3);
        doubleLinkedList.list();

    }
}

//创建双向链表
class DoubleLinkedList{
    //创建头节点
    private HeroNode2 head = new HeroNode2(0,"","");

    public HeroNode2 getHead(){
        return head;
    }

    //遍历单链表
    public void list(){
        //判断链表是否为空
        if(head.next == null){
            System.out.println("链表为空");
            return;
        }

        HeroNode2 temp = head.next;
        while(temp != null){

            System.out.println(temp);
            temp = temp.next;
        }
    }

    //尾插法增加节点
    public void add(HeroNode2 hero){
        //通过辅助变量来判断是否到达链表最后一个节点
        HeroNode2 temp = head;
        while(true){

            if(temp.next == null){
                break;
            }
            temp = temp.next;
        }
        hero.next = temp.next;
        temp.next = hero;
        hero.pre = temp;
    }

    //根据编号修改节点信息
    public void update(HeroNode2 newHeroNode){
        HeroNode2 temp = head.next;
        boolean flag = false;

        while(true){
            if(temp == null ){
                System.out.println("链表为空");
                break;
            }
            if(temp.no == newHeroNode.no){
//                temp.name = newHeroNode.name;
//                temp.nickname = newHeroNode.nickname;
                flag = true;
                break;
            }
            temp = temp.next;
        }
        if(flag){ // 找到要更新信息节点的编号，进行更新
            temp.name = newHeroNode.name;
            temp.nickname = newHeroNode.nickname;
        }else{  //编号节点不存在，不能修改
            System.out.printf("没有找到编号为%d的节点，不能修改！",newHeroNode.no);
        }
    }

    //根据编号删除节点

    /**
     * 1.对于双向链表，可以直接找到要删除的节点，不需要像单链表一样找要删除节点的前一个节点
     * @param no
     */
    public void delete(int no){

        if(head.next == null){
            System.out.println("链表为空，无法删除！");
            return;
        }

        HeroNode2 temp = head.next;
        boolean flag = false;
        while(true){
            if(temp == null){  //没有找到要删除的节点
                break;
            }
            if(temp.no == no){
                flag = true;
                break;
            }
            temp = temp.next;
        }
        if(flag){
            temp.pre.next = temp.next;
            if(temp.next != null){
                temp.next.pre = temp.pre;  //最后一个节点不需要执行此条语句，否则会出现空指针异常
            }
        }else{
            System.out.printf("没有找到编号为%d的节点，不能删除！",no);
        }
    }

    //按顺序添加节点
    public void addByOrder(HeroNode2 hero){
        //因为是单链表，所以找到的节点必须位于要插入节点的前一个节点
        HeroNode2 temp = head;
        boolean flag = false;  //标志添加的编号是否存在，默认为false
        while(true){
            if(temp.next == null ){  //说明temp已经在链表尾部
                break;
            }
            if( temp.next.no > hero.no){  //位置找到，在temp节点后面插入当前节点
//                hero.next = temp.next;
//                temp.next = hero;
                break;
            }else if(temp.next.no == hero.no ){  //要添加的编号已经存在
                flag = true;
                break;
            }
            temp = temp.next;  //继续遍历单链表
        }

        //判断flag
        if(flag){  //编号存在，不能加入
            System.out.printf("当前编号%d已经存在，不能加入！\n",hero.no);
        }else{
            hero.next = temp.next;
            temp.next.pre = hero;
            temp.next = hero;
            hero.pre = temp;

        }
    }

}

//创建节点
class HeroNode2{
    public int no;
    public String name;
    public String nickname;
    public HeroNode2 next;
    public HeroNode2 pre;

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

    @Override
    public String toString() {
        return "HeroNode{" +
                "no=" + no +
                ", name='" + name + '\'' +
                ", nickname='" + nickname + '\'' +
                '}';
    }
}