What is a linked list in java

LinkedList uses a circular doubly linked list data structure. Compared with array-based ArrayList, these are two completely different implementation technologies, which also determines that they will be suitable for completely different work scenarios.

Linked list is a common basic data structure. It is a linear table, but it does not store data in linear order, but in each A pointer to the next node is stored in one node.

Using the linked list structure can overcome the shortcoming of the array linked list that the data size needs to be known in advance. The linked list structure can make full use of the computer memory space and achieve flexible dynamic memory management. However, the linked list loses the advantage of random reading of the array, and at the same time, the space overhead of the linked list is relatively large due to the increase of the pointer field of the node.

Example:

package com.ys.link;

public class DoublePointLinkedList {
    private Node head;//头节点
    private Node tail;//尾节点
    private int size;//节点的个数
    
    private class Node{
        private Object data;
        private Node next;
        
        public Node(Object data){
            this.data = data;
        }
    }
    
    public DoublePointLinkedList(){
        size = 0;
        head = null;
        tail = null;
    }
    
    //链表头新增节点
    public void addHead(Object data){
        Node node = new Node(data);
        if(size == 0){//如果链表为空，那么头节点和尾节点都是该新增节点
            head = node;
            tail = node;
            size++;
        }else{
            node.next = head;
            head = node;
            size++;
        }
    }
    
    //链表尾新增节点
    public void addTail(Object data){
        Node node = new Node(data);
        if(size == 0){//如果链表为空，那么头节点和尾节点都是该新增节点
            head = node;
            tail = node;
            size++;
        }else{
            tail.next = node;
            tail = node;
            size++;
        }
    }
    
    //删除头部节点，成功返回true，失败返回false
    public boolean deleteHead(){
        if(size == 0){//当前链表节点数为0
            return false;
        }
        if(head.next == null){//当前链表节点数为1
            head = null;
            tail = null;
        }else{
            head = head.next;
        }
        size--;
        return true;
    }
    //判断是否为空
    public boolean isEmpty(){
        return (size ==0);
    }
    //获得链表的节点个数
    public int getSize(){
        return size;
    }
    
    //显示节点信息
    public void display(){
        if(size >0){
            Node node = head;
            int tempSize = size;
            if(tempSize == 1){//当前链表只有一个节点
                System.out.println("["+node.data+"]");
                return;
            }
            while(tempSize>0){
                if(node.equals(head)){
                    System.out.print("["+node.data+"->");
                }else if(node.next == null){
                    System.out.print(node.data+"]");
                }else{
                    System.out.print(node.data+"->");
                }
                node = node.next;
                tempSize--;
            }
            System.out.println();
        }else{//如果链表一个节点都没有，直接打印[]
            System.out.println("[]");
        }
    }

}

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