变量和事件问题的范围 [英] scope of variables and events problem

问题描述

我在这里使用FileSystemWatcher，并且我希望保留在应用程序会话期间创建的所有文件的数组列表.
因此，在文件系统上发生事件之后，我想将文件添加到数组中.
现在，这不起作用.但是如何正确实施它.

片段

I am working here with FileSystemWatcher, and i want to keep an arraylist of all the files created during the session of the application.
So after and event on the filesystem i want to add the file to the array.
Now this doesn''t work. But how to implement it the right way.

snippit

class Import
{
   private ArrayList a;
   private FileSystemWatcher f;
   public Import()
   {
      // create and configure Arraylist and FileWatcher here
      
      f.Changed += new FileSystemEventHandler(OnChanged);
   }
   private static void OnChanged(object source, FileSystemEventArgs args)
   {
      // Here i cannot access the Arraylist a to add the args. to it.
   }
}

对不起，新手级别

Sorry for the newbie level

推荐答案

添加到John的答案中:

该代码中的两个问题(尽管这可能不是您的实际代码)

1.您没有在任何地方实例化FileSystemWatcher .

2.将OnChanged 设为非static 方法，它将可以访问a成员.

意见建议:

1.将a设置为List<>而不是ArrayList.

2.将a重命名为更有意义的名称.

Adding to John''s answer:

Two problems in that code (although this may not be your actual code)

1. You are not instantiating your FileSystemWatcher anywhere.

2. Make OnChanged a non-static method and it will be able to access the a member.

Suggestions:

1. Make a a List<> instead of an ArrayList.

2. Rename a to something more meaningful.

您可能想看看我的两部分文章系列.它不会完全回答您的问题，但它应该提供启发和使用FileSystemWatcher对象的更好方法:

FileSystemWatcher-纯混沌(第1部分，共2部分) [ FileSystemWatcher-纯粹的混乱(第2部分，共2部分) [

You might want to check out my two-part article series. It won''t precisely answer your question, but it should provide enlightenment and a better way to use the FileSystemWatcher object:

FileSystemWatcher - Pure Chaos (Part 1 of 2)[^]

FileSystemWatcher - Pure Chaos (Part 2 of 2)[^]

因为您的方法是static如果您想通过该方法使用成员，也可以使其成为static.

Since your method is static you have to make your members static as well if you want to use them from that method.

static private ArrayList a;

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