可以将Java的NullPointerException更改为报告哪个变量为null吗? [英] Can Java's NullPointerException be changed to report on which variable was null?

问题描述

Java中的 NullPointerException 似乎仅报告它发生在特定的代码行上.如果在一行代码中使用多个变量，是否可以更改该异常以声明哪个变量为null?

The NullPointerException in Java seems to only report that it occurred on a particular line of code. Is it possible to alter that exception to state which variable was null if there is more than one variable used in a line of code?

推荐答案

否，类文件中的调试信息包含的信息不足以允许此操作.

No, the debug information in the class file does not contain enough information to allow this.

但是，您可以改善这种情况.可以导致抛出NPE的原因有两点:

You can, however, improve on the situation. There are two things that can cause a NPE to be thrown:

• 取消引用变量的.，例如 foo.bar().
• 一个 [为数组建立索引，例如 args [0] .

• A . dereferencing a variable, like foo.bar().
• A [ indexing an array, like args[0].

如果您编写代码，那么在给定的代码行中只有其中的 个，则毫无疑问，是哪个代码导致了NPE.它将引入一个 lot 临时变量，但是在调试时，您将获得更多可用信息.

If you write your code so there is only one of these on a given code line, there is simply no doubt about which one caused the NPE. It will introduce a lot of temporary variables but then you have more information readily available when debugging.

这篇关于可以将Java的NullPointerException更改为报告哪个变量为null吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！