On Thu, 3 Sep 2026 06:56:05 GMT, Tushar saini <[email protected]> wrote:

> ## Summary
> 
> [`JDK-8223933`](https://bugs.openjdk.org/browse/JDK-8223933)
> 
> `Stream.distinct()` must remove duplicates according to `Object.equals`. On 
> sorted streams it only compared each element to the previous one, which fails 
> when `compareTo` is inconsistent with `equals`, so duplicates can still be 
> emitted.
> 
> ## Fix
> Keep the sorted-path consecutive check, and also track emitted elements in a 
> `HashSet` so uniqueness always follows `equals`. Add a regression test for 
> the reported case and for equals-duplicates in different sort groups.
> 
> ---------
> - [x] I confirm that I make this contribution in accordance with the [OpenJDK 
> Interim AI Policy](https://openjdk.org/legal/ai).

Just weighing in: I suspect that this isn't really solvable without risking 
breakage. If `sorted()` is to also enforce that `prev.compareTo(next)` is 
aligned with the result of `prev.equals(next)` then usages that are currently 
working will cease to work: 


jshell> (new BigDecimal("0.0")).compareTo(new BigDecimal("0.00"))
$1 ==> 0

jshell> (new BigDecimal("0.0")).equals(new BigDecimal("0.00"))
$2 ==> false


If instead a distinct() following a sorted() always re-processes the entire 
Stream, then it would risk changing the output of existing Stream usages 
(silently). 🤔

-------------

PR Comment: https://git.openjdk.org/jdk/pull/32670#issuecomment-5526700187

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