有效沟通问答-【官方】百战程序员_IT在线教育培训机构

package com.baizhan.test;

public class MuLinkedList1<E> implements MyList<E>{
    class Node<E>{
        E item;
        Node next;

        public Node(E item, Node next) {
            this.item = item;
            this.next = next;
        }
    }
    private Node head;
    private  int size;
    @Override
    public void add(E element) {
        Node<E> node=new Node<>(element,null) ;
        Node tail=getTail();
        if(tail==null){
           head=node;
        }else{
            tail.next=node;
        }
        size++;
    }
  private  Node getTail(){

        if(this.head==null){
            return null;
        }else{
            Node node=head;
           for(int i=0;i<size-1;i++){
               if(node.next==null) break;
               node=node.next;
           }
           return  node;
        }

  }
    @Override
    public E get(int index) {
        chickIndex(index);
        Node<E> node=getNode(index);
        return node.item;
    }
    public void chickIndex(int index){
     if(!(index>0&&index<size)) {
         throw new IndexOutOfBoundsException("Index:"+index+"size"+size);
     }
}
private Node getNode(int index){
        Node<E> node=head;
        for(int i=0;i<index;i++){
            node=node.next;
        }
        return node;
}
    @Override
    public int size() {
        return size;
    }

    @Override
    public E remove(int index) {
        chickIndex(index);
        Node<E> node=this.getNode(index);
        E item=node.item;
        if(this.head==node){
           this.head==node.next;
        }else{
            Node<E> temp=head;
            for(int i=0;i<index-1;i++){
                temp=temp.next;
            }
            temp.next=node.next;
             node.next == null;
        }
       
        this.size--;
        return item;
    }
}

老师，这两个地方为啥会报错

JAVA 全系列/第二阶段：JAVA 基础深化和提高/数据结构 24445楼

没有转码成功是什么原因

Python 全系列/第十阶段：前端进阶-高效开发Vue框架/ES6新特性 24446楼

老师好，请看一下：

问题：无法获取Goods类的brand属性

商品类：

package cn.sxt.thread;

public class Goods {

private String name;

private String brand;

private boolean flag;

JAVA 全系列/第二阶段：JAVA 基础深化和提高/网络编程（旧） 24447楼

老师，这是结果报的是NoneType: None，应该怎么办啊

2024-05-21 12:35:46 [scrapy.utils.log] INFO: Scrapy 2.11.2 started (bot: scrapy05)

2024-05-21 12:35:46 [scrapy.utils.log] INFO: Versions: lxml 5.2.2.0, libxml2 2.11.7, cssselect 1.2.0, parsel 1.9.1, w3lib 2.1.2, Twisted 24.3.0, Python 3.11.3 (tags/v3.11.3:f3909b8, Apr 4 2023, 23:49:59) [MSC v.1934 64 bit (AMD64)], pyOpenSSL 24.1.0 (OpenSSL 3.2.1 30 Jan 2024), cryptography 42.0.7, Platform Windows-10-10.0.22621-SP0

2024-05-21 12:35:46 [scrapy.addons] INFO: Enabled addons:

[]

2024-05-21 12:35:46 [asyncio] DEBUG: Using selector: SelectSelector

2024-05-21 12:35:46 [scrapy.utils.log] DEBUG: Using reactor: twisted.internet.asyncioreactor.AsyncioSelectorReactor

2024-05-21 12:35:46 [scrapy.utils.log] DEBUG: Using asyncio event loop: asyncio.windows_events._WindowsSelectorEventLoop

2024-05-21 12:35:46 [scrapy.extensions.telnet] INFO: Telnet Password: 9681eb48711cc975

2024-05-21 12:35:46 [scrapy.middleware] INFO: Enabled extensions:

['scrapy.extensions.corestats.CoreStats',

'scrapy.extensions.telnet.TelnetConsole',

'scrapy.extensions.logstats.LogStats']

2024-05-21 12:35:46 [scrapy.crawler] INFO: Overridden settings:

{'BOT_NAME': 'scrapy05',

'FEED_EXPORT_ENCODING': 'utf-8',

'NEWSPIDER_MODULE': 'scrapy05.spiders',

'REQUEST_FINGERPRINTER_IMPLEMENTATION': '2.7',

'SPIDER_MODULES': ['scrapy05.spiders'],

'TWISTED_REACTOR': 'twisted.internet.asyncioreactor.AsyncioSelectorReactor',

'USER_AGENT': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 '

'(KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36'}

2024-05-21 12:35:46 [scrapy.middleware] INFO: Enabled downloader middlewares:

['scrapy.downloadermiddlewares.offsite.OffsiteMiddleware',

'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',

'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',

'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',

'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',

'scrapy.downloadermiddlewares.retry.RetryMiddleware',

'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',

'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',

'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',

'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',

'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware',

'scrapy.downloadermiddlewares.stats.DownloaderStats']

2024-05-21 12:35:46 [scrapy.middleware] INFO: Enabled spider middlewares:

['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',

'scrapy.spidermiddlewares.referer.RefererMiddleware',

'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',

'scrapy.spidermiddlewares.depth.DepthMiddleware']

2024-05-21 12:35:46 [scrapy.middleware] INFO: Enabled item pipelines:

['scrapy.pipelines.images.ImagesPipeline']

2024-05-21 12:35:46 [scrapy.core.engine] INFO: Spider opened

2024-05-21 12:35:46 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)

2024-05-21 12:35:46 [scrapy.extensions.telnet] INFO: Telnet console listening on 127.0.0.1:6023

2024-05-21 12:35:46 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://desk.zol.com.cn/bizhi/9812_118227_2.html> (referer: None)

2024-05-21 12:35:46 [scrapy.downloadermiddlewares.offsite] DEBUG: Filtered offsite request to 'desk-fd.zol-img.com.cn': <GET https://desk-fd.zol-img.com.cn/t_s960x600c5/g6/M00/0F/09/ChMkKWF4tn6IeIGwAD5r3l1JSDcAAU-5QFAFu4APmv2924.jpg>

2024-05-21 12:35:46 [scrapy.pipelines.media] ERROR: [Failure instance: Traceback: <class 'scrapy.pipelines.files.FileException'>:

D:\python_env\spider3_env\Lib\site-packages\twisted\internet\defer.py:536:addCallbacks

D:\python_env\spider3_env\Lib\site-packages\twisted\internet\defer.py:1078:_runCallbacks

D:\python_env\spider3_env\Lib\site-packages\scrapy\pipelines\media.py:197:_check_media_to_download

D:\python_env\spider3_env\Lib\site-packages\twisted\internet\defer.py:536:addCallbacks

--- <exception caught here> ---

D:\python_env\spider3_env\Lib\site-packages\twisted\internet\defer.py:1078:_runCallbacks

D:\python_env\spider3_env\Lib\site-packages\scrapy\pipelines\files.py:459:media_failed

]

NoneType: None

2024-05-21 12:35:46 [scrapy.core.scraper] DEBUG: Scraped from <200 https://desk.zol.com.cn/bizhi/9812_118227_2.html>

{'image_urls': ['https://desk-fd.zol-img.com.cn/t_s960x600c5/g6/M00/0F/09/ChMkKWF4tn6IeIGwAD5r3l1JSDcAAU-5QFAFu4APmv2924.jpg'], 'images': []}

2024-05-21 12:35:46 [scrapy.core.engine] INFO: Closing spider (finished)

2024-05-21 12:35:46 [scrapy.statscollectors] INFO: Dumping Scrapy stats:

{'downloader/exception_count': 1,

'downloader/exception_type_count/scrapy.exceptions.IgnoreRequest': 1,

'downloader/request_bytes': 316,

'downloader/request_count': 1,

'downloader/request_method_count/GET': 1,

'downloader/response_bytes': 9739,

'downloader/response_count': 1,

'downloader/response_status_count/200': 1,

'elapsed_time_seconds': 0.367081,

'finish_reason': 'finished',

'finish_time': datetime.datetime(2024, 5, 21, 4, 35, 46, 984841, tzinfo=datetime.timezone.utc),

'httpcompression/response_bytes': 33794,

'httpcompression/response_count': 1,

'item_scraped_count': 1,

'log_count/DEBUG': 6,

'log_count/ERROR': 1,

'log_count/INFO': 10,

'offsite/domains': 1,

'offsite/filtered': 1,

'response_received_count': 1,

'scheduler/dequeued': 1,

'scheduler/dequeued/memory': 1,

'scheduler/enqueued': 1,

'scheduler/enqueued/memory': 1,

'start_time': datetime.datetime(2024, 5, 21, 4, 35, 46, 617760, tzinfo=datetime.timezone.utc)}

2024-05-21 12:35:46 [scrapy.core.engine] INFO: Spider closed (finished)

Python 全系列/第十六阶段：Python 爬虫开发/scrapy框架使用 24448楼

或者是用？但是必须加上数字，这种方法方法，参数列表的，入参顺序必须与 @Query注解当中标注的顺序相同

JAVA 全系列/（旧的隐藏）第十一阶段：spring全家桶（Spring Boot）/Spring Boot 24449楼

老师，浅拷贝是不是，增加b除了复制a里的数据，b内部发生了变化，也同样会给a拷贝b内部的数据。

而深拷贝b发生了变化后，a不发生任何变化。

Python 全系列/第一阶段：AI驱动的Python编程/函数和内存分析 24450楼

关闭

关于

课程分类

百战程序员微信公众号

百战程序员微信小程序

同学您好