On Feb 21 2014, at 14:56 , Martin Buchholz <[email protected]> wrote:
> You should do <tt> -> code conversion separately, and do it pervasively
> across the entire JDK.
From your lips to God's ears.... I keep suggesting this along with a restyle to
official style every time we create new repos. Seems unlikely unfortunately as
it makes backports harder.
> This is not right.
> + * {@code
> (o==null ? get(i)==null : o.equals(get(i)))}
Corrected.
> You accidentally deleted a stray space here?
>
> - this.elementData = EMPTY_ELEMENTDATA;
> + this.elementData = EMPTY_ELEMENTDATA;
Corrected.
> public ArrayList(int initialCapacity) {
> - super();
> if (initialCapacity < 0)
> throw new IllegalArgumentException("Illegal Capacity: "+
> initialCapacity);
> - this.elementData = new Object[initialCapacity];
> + this.elementData = (initialCapacity > 0)
> + ? new Object[initialCapacity]
> + : EMPTY_ELEMENTDATA;
> }
>
> When optimizing for special cases, we should try very hard minimize overhead
> in the common case. In the above, we now have two branches in the common
> case. Instead,
>
> if (initialCapacity > 0) this.elementData = new Object[initialCapacity];
> else if (initialCapacity == 0) this.elementData = EMPTY_ELEMENTDATA;
> else barf
Corrected.
Thanks as always for the feedback.
Mike
>
>
>
> On Fri, Feb 21, 2014 at 2:41 PM, Mike Duigou <[email protected]> wrote:
> Hello all;
>
> This changeset consists of two small performance improvements for ArrayList.
> Both are related to the lazy initialization introduced in JDK-8011200.
>
> The first change is in the ArrayList(int capacity) constructor and forces
> lazy initialization if the requested capacity is zero. It's been observed
> that in cases where zero capacity is requested that it is very likely that
> the list never receives any elements. For these cases we permanently avoid
> the allocation of an element array.
>
> The second change, noticed by Gustav Åkesson, involves the
> ArrayList(Collection c) constructor. If c is an empty collection then there
> is no reason to inflate the backing array for the ArrayList.
>
> http://cr.openjdk.java.net/~mduigou/JDK-8035584/0/webrev/
>
> I also took the opportunity to the <tt></tt> -> {@code } conversion for the
> javadoc.
>
> Enjoy!
>
> Mike
>
