On Fri, 12 Feb 2021 22:52:06 GMT, Joe Darcy <da...@openjdk.org> wrote:
>> A follow-up of sorts to JDK-8257086, this change aims to improve the
>> discussion of the relationship between Object.equals and compareTo and
>> compare methods. The not-consistent-with-equals natural ordering of
>> BigDecimal get more explication too. While updating Object, I added some
>> uses of apiNote and implSpec, as appropriate. While a signum method did not
>> exist when Comparable was added, it has existed for many years so I removed
>> obsolete text that defined a "sgn" function to compute signum.
>>
>> Once the changes are agreed to, I'll reflow paragraphs and update the
>> copyright years.
>
> Joe Darcy has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Fix typo.
Marked as reviewed by smarks (Reviewer).
src/java.base/share/classes/java/math/BigDecimal.java line 99:
> 97: * hold. The results of methods like {@link scale} and {@link
> 98: * unscaledValue} will differ for numerically equal values with
> 99: * different representations.
While this text is correct and reasonable, it doesn't really explain _why_
equals() considers the representation. One might assume incorrectly that the
representation is internal only and doesn't affect computations. Of course it
does affect computations, which is why I suggested the example. Maybe the
example doesn't belong right here, in which case it's reasonable for this
change to proceed. I think it would be good to put an example _somewhere_ of
non-substitutability of numerical values with different representations. Maybe
we could handle that separately.
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PR: https://git.openjdk.java.net/jdk/pull/2471
