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作为开发人员，我们经常遇到这种异常：NullReferenceException众所周知的错误消息：

你调用的对象是空的

.NET 框架不可能返回更有意义的东西吗？

例如：

名为 Y 的 X 类型对象未设置为对象的实例

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3 回答 3

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An object doesn't have a name - so how can it tell you the name? The null reference may have been loaded from a variable - or it might have been returned by a method, property etc.

The JIT could probably look at the stack information to work out what the declared reference type was, but I'm not sure how often this would help - and doubtless it would slow things down.

I can't say I've ever found this to be a huge burden when it comes to debugging - if there are lots of things which can be null on a single line, that usually suggests that it's worth splitting them up more.

于 2010-01-14T16:30:46.813 回答
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对我来说，这似乎纯粹是一个偏好问题。如果它让你烦恼那么多，你总是可以继承NullReferenceException并更改消息。:)

它归结为创建消息时可用的信息量。在不手动传递一些额外信息的情况下，简单地确定其中为 null 的字段的名称NullReferenceException将需要反射（可能相当多），这是一个相当繁重的操作。例如ArgumentNullException，为了抛出一个消息指示有问题的参数名称，您必须在调用它时传入一个字符串：throw new ArgumentNullException("param1")。

异常消息中的详细程度完全取决于定义它的程序员，但在引发异常时避免做任何系统密集的事情是谨慎的。

于 2010-01-14T16:36:11.437 回答
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Because its the most generic way of saying that.

于 2010-01-14T16:30:40.427 回答