LinkedList底层机制

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   package com.model.linkedlist;
   
   /**
    * @Description:测试类
    * @Author: 张紫韩
    * @Crete 2021/6/12 9:21
    */
   public class LinkedListDemo01 {
   
       public static void main(String[] args) {
   //         模拟一个双向链表
           Node a=new Node("a");
           Node b=new Node("b");
           Node c=new Node("c");
           Node first=a;
           Node last=c;
           a.next=b;
           b.next=c;
           c.pre=b;
           b.pre=a;
   
           while(true){
               if (first==null){
                   break;
               }
               System.out.println(first.toString());
               first=first.next;
           }
           while(true){
               if (last==null){
                   break;
               }
               System.out.println(last.toString());
               last=last.pre;
           }
   
           //添加一个元素,在a和b之间
           Node B=new Node("B");
           B.next=b;
           B.pre=a;
           b.pre=B;
           a.next=B;
           //循环遍历验证
           first=a;
           last=c;
           while(true){
               if (first==null){
                   break;
               }
               System.out.println(first.toString());
               first=first.next;
           }
   
       }
   }
   
   class Node{
       protected Node next;
       protected Node pre;
       protected Object item;
   
       public Node(Object item) {
           this.item = item;
       }
   
       @Override
       public String toString() {
           return "Node{" +
                   "item=" + item +
                   '}';
       }
   }

LinkedList底层结构

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2. 执行 ：new LinkedList（）；

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3. 执行 linkedList.add()

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4. 执行 linkedList.remove(1);

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   4. package com.model.linkedlist;
      
      import java.util.Iterator;
      import java.util.LinkedList;
      import java.util.List;
      
      /**
       * @Description:测试类
       * @Author: 张紫韩
       * @Crete 2021/6/12 9:49
       */
      public class LinkedListDemo02 {
      
          public static void main(String[] args) {
              List<Object> linkedList = new LinkedList<>();
              linkedList.add("zzh");
              linkedList.add("zzh1");
              linkedList.add("zzh2");
              linkedList.remove(1);
      
              Iterator<Object> iterator = linkedList.iterator();
              while (iterator.hasNext()) {
                  Object next =  iterator.next();
                  System.out.println(next);
              }
              for (Object o:linkedList){
                  System.out.println(o);
              }
              for (int i=0;i<linkedList.size();i++){
                  System.out.println(linkedList.get(i));
              }
      
      
          }
          /**
           * CRUD:增删改查
           *
           * 1.new LinkedList():
           *
           *    public LinkedList() {
           *     }
           *     这是first，last，size都为空
           * 2.
           * */
      }

       

ArrayList和LinkedList的比较