Having a List.of(List) copy constructor would save an additional array copy in the collector Which uses (List<T>)List.of(list.toArray())
Gruss Bernd -- http://bernd.eckenfels.net ________________________________ From: core-libs-dev <core-libs-dev-boun...@openjdk.java.net> on behalf of Stuart Marks <stuart.ma...@oracle.com> Sent: Wednesday, November 1, 2017 12:49:56 AM To: core-libs-dev Subject: Re: RFR(m): 8177290 add copy factory methods for unmodifiable List, Set, Map Updated webrev, based on comments from Brian and Roger: http://cr.openjdk.java.net/~smarks/reviews/8177290/webrev.2/ s'marks On 10/30/17 3:50 PM, Stuart Marks wrote: > (also includes 8184690: add Collectors for collecting into unmodifiable List, > Set, and Map) > > Hi all, > > Here's an updated webrev for this changeset; the previous review thread is > here: > > > http://mail.openjdk.java.net/pipermail/core-libs-dev/2017-September/049261.html > > This webrev includes the following: > > * specification revisions to provide clearer definitions of "view" > collections, > "unmodifiable" collections, and "unmodifiable views" > > * new List.copyOf(), Set.copyOf(), and Map.copyOf() "copy factory" methods > > * new Collectors.toUnmodifiableList, Set, and Map methods > > * tests for the new API methods > > I've added some assertions that require some independence between the source > collection (or map) and the result of the copyOf() method. > > I've made a small but significant change to Set.copyOf compared to the > previous > round. Previously, it specified that the first of any equal elements was > preserved. Now, it is explicitly unspecified which of any equals elements is > preserved. This is consistent with Set.addAll, Collectors.toSet, and the newly > added Collectors.toUnmodifiableSet, none of which specify which of duplicate > elements is preserved. > > (The outlier here is Stream.distinct, which specifies that the first element > of > any duplicates is preserved, if the stream is ordered.) > > I've also made some minor wording/editorial changes in response to suggestions > from David Holmes and Roger Riggs. I've kept the wording changes that give > emphasis to "unmodifiable" over "immutable." The term "immutable" is > inextricably intertwined with "persistent" when it comes to data structures, > and > I believe we'll be explaining this forever if Java's "immutable" means > something > different from everybody else's. > > Webrev: > > http://cr.openjdk.java.net/~smarks/reviews/8177290/webrev.1/ > > Bugs: > > https://bugs.openjdk.java.net/browse/JDK-8177290 > add copy factory methods for unmodifiable List, Set, Map > > https://bugs.openjdk.java.net/browse/JDK-8184690 > add Collectors for collecting into unmodifiable List, Set, and Map > > Thanks, > > s'marks
