RFR 8132964 Spliterator documentation on Priority(Blocking)Queue

[Doug Lea]

On 11/21/2016 03:52 PM, Paul Sandoz wrote:
> Hi,
>
> Please review specification clarifications to PriorityQueue and PriorityBlockingQueue for the spliterator. Ordinarily i would not specify what spliterator characteristics are not reported, but in this case given what is said about iterator I think it reasonable to say it about spliterator (a number of developers have got caught out regarding order, or lack thereof in this case, but i also suspect they never read the specification!)
>

Sure. It would be nice if there were something we could do to reduce
confusion between ordered-but-destructive poll()-loops, vs unordered
but-read-only iterators/spliterators. But clarifying here might help
a little.

-Doug


> Paul.
>
> diff -r eb147f1f232d src/java.base/share/classes/java/util/PriorityQueue.java
> --- a/src/java.base/share/classes/java/util/PriorityQueue.java	Mon Nov 21 12:00:46 2016 -0800
> +++ b/src/java.base/share/classes/java/util/PriorityQueue.java	Mon Nov 21 12:30:33 2016 -0800
> @@ -54,7 +54,8 @@
>   * <p>This class and its iterator implement all of the
>   * <em>optional</em> methods of the {@link Collection} and {@link
>   * Iterator} interfaces.  The Iterator provided in method {@link
> - * #iterator()} is <em>not</em> guaranteed to traverse the elements of
> + * #iterator()} and the Spliterator provided in method {@link #spliterator()}
> + * are <em>not</em> guaranteed to traverse the elements of
>   * the priority queue in any particular order. If you need ordered
>   * traversal, consider using {@code Arrays.sort(pq.toArray())}.
>   *
> @@ -799,7 +800,8 @@
>      /**
>       * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
>       * and <em>fail-fast</em> {@link Spliterator} over the elements in this
> -     * queue.
> +     * queue. The spliterator does not traverse elements in any particular order
> +     * (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
>       *
>       * <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
>       * {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
> diff -r eb147f1f232d src/java.base/share/classes/java/util/concurrent/PriorityBlockingQueue.java
> --- a/src/java.base/share/classes/java/util/concurrent/PriorityBlockingQueue.java	Mon Nov 21 12:00:46 2016 -0800
> +++ b/src/java.base/share/classes/java/util/concurrent/PriorityBlockingQueue.java	Mon Nov 21 12:30:33 2016 -0800
> @@ -65,7 +65,8 @@
>   * <p>This class and its iterator implement all of the
>   * <em>optional</em> methods of the {@link Collection} and {@link
>   * Iterator} interfaces.  The Iterator provided in method {@link
> - * #iterator()} is <em>not</em> guaranteed to traverse the elements of
> + * #iterator()} and the Spliterator provided in method {@link #spliterator()}
> + * are is <em>not</em> guaranteed to traverse the elements of
>   * the PriorityBlockingQueue in any particular order. If you need
>   * ordered traversal, consider using
>   * {@code Arrays.sort(pq.toArray())}.  Also, method {@code drainTo}
> @@ -994,6 +995,8 @@
>
>      /**
>       * Returns a {@link Spliterator} over the elements in this queue.
> +     * The spliterator does not traverse elements in any particular order
> +     * (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
>       *
>       * <p>The returned spliterator is
>       * <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>.
>