RFR: 8001647: In-place methods on Collection/List

[Arne Siegel]

On 7 Dec 2012 at 17:42, Akhil Arora wrote:

> As part of the Library Lambdafication, this patch adds the following 
> default methods to Collections -
> 
> Iterable.forEach(Block<T>)
> Collection.removeAll(Predicate<T>)
> List.sort(Comparator)
> List.replaceAll(UnaryOperator<T>)
> 
> It also provides more efficient implementations of these methods for 
> ArrayList, Vector and CopyOnWriteArrayList. Please review.
> 
> http://cr.openjdk.java.net/~akhil/8001647.1/webrev/
> 
> Thanks to the many people who have already contributed to this patch.
> 

I took a look at the ArrayList implementation. To my understanding it works fine, just got a 
few observations.

ArrayList.java, line 1171:
        final boolean anyToRemove = (removeSet != null) && !removeSet.isEmpty();
As removeSet will never be null, this line can be simplified. This is a left-over from the 
preceding implementation (see b67).

ArrayList.java, method forEach optimizes the loop by reducing the number of heap accesses:
        final int size = this.size;
        for (int i=0; modCount == expectedModCount && i < size; i++) {
            ...
This trick might also be introduced to methods removeAll and replaceAll.

In the ListIterator implementation of ArrayList, there are various appearances of the idiom:
                    try {
                        ...
                    } catch (IndexOutOfBoundsException ex) {
                        throw new ConcurrentModificationException();
                    }
This technique might also be used in forEach, removeAll, and replaceAll (though not likely to 
be of any importance).

Regards
Arne Siegel