为什么 Double.parseDouble (null)和 Integer.parseInt (null)抛出不同的异常？

这是历史意外还是故意的？文件明确说明了 Double.parseDouble(...)和 Integer.parseInt()的两种例外情况，但似乎不一致:

Integer.parseInt(null); // throws java.lang.NumberFormatException: null

然而

Double.parseDouble(null); // throws java.lang.NullPointerException

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Note: everything in this post is in the source of Java7-b147

Double.parseDouble() goes into a Sun library (in sun.misc.FloatingDecimal) the first important thing that happens is:

in = in.trim(); // don't fool around with white space.
// throws NullPointerException if null

Integer.parseInt() is done manually in the Integer class. The first important thing that happens is:

if (s == null) {
throw new NumberFormatException("null");
}

I would guess there are two different authors.

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最佳答案

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.

And:

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.

As taken from: Bug Report: Integer.parseInt() and Double.parseDouble() throw different exceptions on null.

Like others have stated: It's likely made by different authors.