In "View Collections"
Most collections contain elements themselves. By contrast, <i>view
collections</i>
112 * themselves do not contain elements, but instead rely on a backing
collection to
113 * store the actual elements.
This should be: "most collections manage the storage for the elements
they contain. By contrast, ...". (All collections contain their
elements -- just ask the `contains()` method!)
Similarly, in:
Correspondingly, any changes made to
126 * the view collection are written through to the backing collection.
you might want to make the connection that views might "handle" the
operation by prohibiting it; view collections need not support changes
if they don't want to.
In
<b>Unmodifiable view collections.</b>
You might want to say explicitly "such as
Collections.unmodifiable{List,Set,...}" when describing unmodifiable
view collections. THat's of course what you're getting at, but it could
be said more explicitly.
Returns an <a href="#unmodifiable">unmodifiable List</a> containing the
elements
1045 * of the given Collection, in iteration order.
In the _given collection's_ iteration order.
Returns an <a href="#unmodifiable">unmodifiable Map</a> containing the
entries
1664 * of the given Map. the given Map must not be null, and it must not
contain any
1665 * null keys or values. If the given Map is subsequently modified,
the returned
1666 * Map will not reflect such modifications.
Second sentence starts with lower case later.
I might quibble with "subsequently modified", as there is some ambiguity
(what if the map is concurrently modified, subsequent to making the
copyOf() call, but prior to the return from copyOf()?) But I won't ;)
In
296 Collector<T, ?, List<T>> toUnmodifiableList() {
297 return new CollectorImpl<>((Supplier<List<T>>) ArrayList::new,
List::add,
298 (left, right) -> { left.addAll(right); return left; },
299 list -> (List<T>)List.of(list.toArray()),
300 CH_NOID);
why the intermediate array, and not just use copyOf()? (Is it because
you added copyOf later and didn't go back and update this?) Same for
other collectors.
On 10/30/2017 6:50 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
