RFR: 8261123: Augment discussion of equivalence classes in Object.equals and comparison methods [v3]

[Joe Darcy]

On Thu, 11 Feb 2021 04:12:06 GMT, Stuart Marks <smarks at openjdk.org> wrote:

>> Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix typos in javadoc tags found during review.
>
> src/java.base/share/classes/java/lang/Comparable.java line 90:
> 
>> 88:  * of the {@code equals} method and the equivalence classes defined by
>> 89:  * the quotient of the {@code compareTo} method are the same.
>> 90:  *
> 
> I think in both cases it should be "the equivalence class defined by...." That is, "equivalence class" should be singular. But there are two of them, so the sentence still properly concludes "... are the same."

An equivalence relation defines a *set* of equivalence classes which partition the objects the relation operates on. For example, the "same signum value" equivalence relation on integers has three equivalence classes :
1) negative nonzero numbers (corresponding to signum == -1)
2) zero (corresponding to signum = 0)
3) positive nonzero numbers (corresponding to signum ==1)

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PR: https://git.openjdk.java.net/jdk/pull/2471