htmlagilitypack链接.属性得到NullReferenceException

本文关键字：NullReferenceException 属性 链接 htmlagilitypack | 更新日期: 2023-09-27 18:17:15

很抱歉有重复，但这个看起来不一样。 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using HtmlAgilityPack;
namespace GetLinks
{
class Program
{
static void Main(string[] args)
{
HtmlDocument doc = new     
HtmlWeb().Load("http://en.wikipedia.org/wiki/Language&#8221");
foreach(HtmlNode link in doc.DocumentNode.SelectNodes("//a"))
{
Console.WriteLine(link.InnerText);
Console.WriteLine(link.Attributes["href"].Value);
}
Console.ReadKey();
}
}

}

所以我使用htmllagilitypack，我得到了错误:

Console.WriteLine(link.Attributes["href"].Value);

错误信息如下:

System.NullReferenceException was unhandled
  HResult=-2147467261
  Message=Object reference not set to an instance of an object.
  Source=ConsoleApplication2
  StackTrace:
   at GetLinks.Program.Main(String[] args) in C:'Users'...'Documents'Visual Studio 2010'Projects'ConsoleApplication2'ConsoleApplication2'Program.cs:line 17
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

如何去尝试解决这些问题?

htmlagilitypack链接.属性得到NullReferenceException

的问题是，你正试图访问一个属性从空值对象，所以你所需要的是检查它是否可以在继续你的代码

将该行改为

var href=link.Attributes["href"];
if (href!=null) Console.WriteLine(href.Value);

我希望它会有帮助。

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