On Sat, 8 Oct 2022 15:35:14 GMT, Tagir F. Valeev <tval...@openjdk.org> wrote:
>> Java 17 added RandomGenerator interface. However, existing method >> Collections.shuffle accepts old java.util.Random class. While since Java 19, >> it's possible to use Random.from(RandomGenerator) wrapper, it would be more >> convenient to provide direct overload shuffle(List<?> list, RandomGenerator >> rnd). > > Tagir F. Valeev has updated the pull request incrementally with one > additional commit since the last revision: > > Remove Random -> ThreadLocalRandom change test/jdk/java/util/Collections/Shuffle.java line 66: > 64: RandomGeneratorFactory<RandomGenerator> factory = > RandomGeneratorFactory.getDefault(); > 65: list.sort(null); > 66: Collections.shuffle(list, factory.create(1)); This assumes that the default factory will accept a seed value that initializes its state so that the pseudorandom sequence is repeatable. Not an unreasonable assumption, but `create(long)` essentially says that it can ignore the seed, and `getDefault` says the algorithm may change over time. On the other hand if something does change such that the pseudorandom sequence isn't repeatable, this test will most likely fail immediately. I was poking around for an explicit way to request some kind of PRNG that's guaranteed to be started in repeatable state, but I couldn't find one. Hmmm. ------------- PR: https://git.openjdk.org/jdk/pull/10520
