实现双向链表的增删改查功能。_编写一个双向链表,实现增删改查-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_27293643/article/details/104999654

实现双向链表的增删改查功能，增加功能分为无序增加和有序增加。

package com.yu.linkedlist;
/**
* 双向链表增删改查询
* @author Administrator
*
*/
public class DoubleLinkedListDemo {

   public static void main(String[] args) {
       User u1 = new User(1,"刘备");
       User u2 = new User(2,"关羽");
       User u3 = new User(3,"张飞");
       User u4 = new User(4,"赵云");
       DoubleLinkedDemo demo = new DoubleLinkedDemo();
       demo.addOrderBy(u2);
       demo.addOrderBy(u4);
       demo.addOrderBy(u1);
       demo.addOrderBy(u3);
       demo.show();
//       System.out.println("修改数据");
//       demo.update(new User(3,"诸葛亮"));
//       demo.show();
//       System.out.println("删除数据...");
//       demo.delete(4);
//       demo.show();
   }
}

/**
* 双向链表的基本操作
* @author Administrator
*
*/
class DoubleLinkedDemo {


   private User user = new User(0,"");//定义一个空参的单向链表

   /**
   * 实现双向链表的有序新增
   * @param u
   */
   public void addOrderBy(User u){
       User temp = user;
       boolean flag1 = false;
       boolean flag2 = false;
       boolean flag3 = false;
       while(true) {
           if(temp.getNext() == null) {
               flag1 = true;
               break;
           }else if(temp.getNext().getNo() > u.getNo()){
               flag2 = true;
               break;
           }else if(temp.getNext().getNo() == u.getNo()) {
               flag3 = true;
               break;
           }
           temp = temp.getNext();
       }
       if(flag1) {
           temp.setNext(u);
           u.setPre(temp);
       }else if(flag2){
           temp.getNext().setPre(u);
           u.setNext(temp.getNext());
           temp.setNext(u);
           u.setPre(temp);

       }else if(flag3) {
           System.out.println("此编号的数据已经存在了");
       }
   }

   /**
   * 无序增加双向链表
   * @param user
   */
   public void add(User u) {
       User temp = user;
       while(temp.getNext() != null) {
           temp = temp.getNext();
       }
       temp.setNext(u);
       u.setPre(temp);
   }

   /**
   * 显示双向链表
   */
   public void show() {
       User temp = user.getNext();
       if(temp == null) {
           System.out.println("单向链表为空...");
           return;
       }
       while(true) {
           if(temp == null) {
               break;
           }
           System.out.println(temp);
           temp = temp.getNext();
       }
   }

   /**
   * 修改双向链表
   */
   public void update(User u) {
       User temp = user.getNext();
       boolean flag = false;
       if(temp == null) {
           System.out.println("双向链表为空...");
           return;
       }
       while(true) {
           if(temp == null) {
               break;
           }else if(temp.getNo() == u.getNo()) {
               flag = true;
               break;
           }
           temp = temp.getNext();
       }
       if(flag) {
           temp.setName(u.getName());
       }else {
           System.out.println("没有找到要修改的编号:" + u.getNo());
       }
   }

   /**
   * 删除双向链表
   */
   public void delete(int no) {
       User temp = user.getNext();
       boolean flag = false;
       if(temp == null) {
           System.out.println("双向链表为空...");
           return;
       }
       while(true) {
           if(temp == null) {
               break;
           }else if(temp.getNo() == no) {
               flag = true;
               break;
           }
           temp = temp.getNext();
       }
       if(flag) {
           temp.getPre().setNext(temp.getNext());
           if(temp.getNext() != null) {
               temp.getNext().setPre(temp.getPre());
           }
       }else {
           System.out.println("没有找到要删除的编号...");
       }
   }
}

/**
* 用户实体信息
* @author Administrator
*
*/
class User {

   private int no;
   private String name;
   private User pre;
   private User next;

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

   public int getNo() {
       return no;
   }
   public void setNo(int no) {
       this.no = no;
   }
   public String getName() {
       return name;
   }
   public void setName(String name) {
       this.name = name;
   }
   public User getPre() {
       return pre;
   }
   public void setPre(User pre) {
       this.pre = pre;
   }
   public User getNext() {
       return next;
   }
   public void setNext(User next) {
       this.next = next;
   }