Java 为什么 Double.parseDouble(null) 和 Integer.parseInt(null) 会抛出不同的异常？
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Why do Double.parseDouble(null) and Integer.parseInt(null) throw different exceptions?
提问by pho79
Why do Double.parseDouble(null) and Integer.parseInt(null) throw different exceptions?
为什么 Double.parseDouble(null) 和 Integer.parseInt(null) 会抛出不同的异常？
Is this a historical accident or intentional? The documentation clearly states two types of exceptions for Double.parseDouble(...)and one for Integer.parseInt(), but it seems inconsistent:
这是历史意外还是有意为之？该文档清楚地说明了两种类型的异常 forDouble.parseDouble(...)和一种 for Integer.parseInt()，但似乎不一致：
Integer.parseInt(null); // throws java.lang.NumberFormatException: null
However
然而
Double.parseDouble(null); // throws java.lang.NullPointerException
采纳答案by Floris Velleman
It is reasonable to expect the same exceptions to be thrown for null; however, these api's are very old and may not be able to be changed at this point.
期望为 null 抛出相同的异常是合理的；但是，这些 api 非常旧，此时可能无法更改。
And:
和：
Since the exception behavior is long-standing and specified in the JavaDoc, it is impractical to change either method's behavior at this time. Closing as will not fix.
由于异常行为长期存在并在 JavaDoc 中指定，因此此时更改任一方法的行为是不切实际的。关闭不会修复。
As taken from: Bug Report: Integer.parseInt() and Double.parseDouble() throw different exceptions on null.
摘自：错误报告：Integer.parseInt() 和 Double.parseDouble() 在 null 上抛出不同的异常。
Like others have stated: It's likely made by different authors.
就像其他人所说的那样：它可能是由不同的作者制作的。
回答by durron597
Note: everything in this post is in the source of Java7-b147
注：本文所有内容均在Java7-b147源码中
Double.parseDouble()goes into a Sun library (in sun.misc.FloatingDecimal) the first important thing that happens is:
Double.parseDouble()进入 Sun 图书馆（在sun.misc.FloatingDecimal），发生的第一件重要事情是：
in = in.trim(); // don't fool around with white space.
// throws NullPointerException if null
Integer.parseInt()is done manually in the Integerclass. The first important thing that happens is:
Integer.parseInt()在Integer课堂上手动完成。发生的第一件重要的事情是：
if (s == null) {
throw new NumberFormatException("null");
}
I would guess there are two different authors.
我猜有两个不同的作者。
