RFR: 8362958: Unnecessary copying / sorting in Streams using Comparator.naturalOrder() [v8]

[Patrick Strawderman]

On Sat, 15 Nov 2025 00:03:40 GMT, Chen Liang <liach at openjdk.org> wrote:

> I don't know about the particular case about TreeSet, but I think with the advent of Comparator.naturalOrder in Java 8, people are much more likely to use it instead of null to represent the natural order, especially for Comparator-returning methods or Comparator fields. Offering such a conversion within the implementation, in my opinion, is better than checking and converting at every single use site that has a Comparator.

I agree with that, I think it seems better to *not* use null to signal natural order. But even if we did that here, the stream classes like `SortedOps` still need to handle null or `Comparator.naturalOrder()`, since the null signaling natural order is part of the contract of SortedSet, Spliterator, etc.

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PR Comment: https://git.openjdk.org/jdk/pull/28226#issuecomment-3535399552