数据结构与算法Java实现-04双向链表

Java双向链表

package aStudy.day2;

import jdk.nashorn.internal.objects.NativeError;

import java.net.HttpRetryException;
import java.sql.SQLOutput;

/**
 * @author haoqi
 * @Date 2020/9/28 - 7:44
 */
public class data02 {

    public static void main(String[] args) {
        //测试
        System.out.println("双向链表测试");
        //创建节点
        HeroNode02 hero1 = new HeroNode02(1,"haoqi","heizi");
        HeroNode02 hero2 = new HeroNode02(2,"dapeng","pangzi");
        HeroNode02 hero3 = new HeroNode02(3,"safei","shouzi");
        HeroNode02 hero4 = new HeroNode02(4,"wuzhen","daizi");
        //创建双向链表
        DoubleLinkedList doubleLinkedList = new DoubleLinkedList();
        doubleLinkedList.add(hero1);
        doubleLinkedList.add(hero2);
        doubleLinkedList.add(hero3);
        doubleLinkedList.add(hero4);
        //输出
        doubleLinkedList.list();

        //修改
        HeroNode02 newheroNode = new HeroNode02(4,"xuchao","shoujian");
        doubleLinkedList.update(newheroNode);
        System.out.println("after the change ");
        doubleLinkedList.list();

        //删除
        doubleLinkedList.delete(1);
        System.out.println("after the delete");
        doubleLinkedList.list();
    }

}


//1.定义HeroNode，链表节点
class HeroNode02{
    public int no;
    public String name;
    public String niloName;
    public HeroNode02 next; //指向下一个节点 默认null
    public HeroNode02 pre; //指向前一个节点//默认为null

    //构造器
    public HeroNode02(int no, String name, String niloName) {
        this.no = no;
        this.name = name;
        this.niloName = niloName;
    }
    //显示方法，重新toString
    @Override
    public String toString() {
        return "LinkList{" +
                "no=" + no +
                ", name='" + name + '\'' +
                ", niloName='" + niloName + '\'' +
                '}';
    }
}

// 1.创建一双向链表
class DoubleLinkedList{
    //1.初始化头节点，Heronode不存放数据
    private HeroNode02 head = new HeroNode02(0,"","");
    //返回
    public HeroNode02 getHead(){
        return head;
    }

    //2.遍历双向链表
    public void list(){
        //判断是否为空
        if (head.next == null){
            System.out.println("链表为空");
            return;
        }
        //头节点不能动，建立辅助节点temp遍历
        HeroNode02 temp = head.next;
        while (true){
            //判断是否到结尾
            if (temp == null)  break;
            //输出节点信息
            System.out.println(temp);
            //后移temp
            temp = temp.next;
        }
    }

    //2.添加一个节点到双向链表结尾
    public void add(HeroNode02 heroNode02){
        //利用辅助节点temp
        HeroNode02 temp = head;
        while (true){
            //判断是否到结尾
            if (temp.next == null)  break;
            //后移temp
            temp = temp.next;
        }
        //当退出while循环时，temp指向了结尾
        //形成一个循环链表
        temp.next = heroNode02;
        heroNode02.pre = temp;
    }

    //3.修改节点的内容，与单项链表节点内容一样
    //稍微修改
    public void update(HeroNode02 newHeroNode){
        //判断是否为空
        if (head.next == null){
            System.out.println("链表为空~");
            return;
        }
        //找到要修改的节点，利用no编号
        HeroNode02 temp = head.next;
        boolean flag = false;
        while (true){
            if (temp == null) break; //遍历结束
            if (temp.no == newHeroNode.no){
                flag = true; //找到了
                break;
            }
            temp = temp.next;
        }
        //利用flag判断是否找到要修改的节点
        if (flag){
            temp.name = newHeroNode.name;
            temp.niloName = newHeroNode.niloName;
        }else
            System.out.printf("没有找到 %d 的节点，不能修改\n", newHeroNode.no);
    }

    //4.从双向链表删除一个节点
    //直接找到要删除的节点，进行自我删除
    public void delete(int no){
        //判断是否为空
        if (head.next == null){
            System.out.println("链表为空，无法删除");
            return;
        }
        HeroNode02 temp = head.next;
        boolean flag = false;
        while (true){
            if (temp == null) break; //遍历结束
            if (temp.no == no){
                flag = true; //找到了
                break;
            }
            temp = temp.next;
        }
        //判断flag
        if (flag){
            temp.pre.next = temp.next;
            //注意
            //如果是最后一个节点，则不执行下面的语句，否则汇报空指针异常
            if (temp.next != null)
                temp.next.pre = temp.pre;
        }else
            System.out.printf("没有找到 %d 的节点，不能修改\n", no);
    }
}