On 12/18/2010 01:31 AM, Mike Duigou wrote:
I've posted a webrev for review at
http://cr.openjdk.java.net/~mduigou/6728865.0/webrev/
which improves the behaviour of Collections.disjoint() when the collection c1
is not a Set and is larger than c2.
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6728865
I've included some other micro-optimizations suggested by the issue and by
common usage.
One optimization, the checks whether either collection is empty using
isEmpty(), may slightly degrade performance relative to the current
implementation but should be a good tradeoff for cases where either of the
collections are empty.
I've also upgraded the javadoc to newer style conventions and included the
missing @return.
Any comments or feedback welcome.
Mike
Hi Mike,
I think that comparing size() is not a good idea because
- for some collections, size() is not a constant operation
- you compare size() when c1 and c2 are sets which
may cause a performance regression because
disjoint(treeSet, hashSet) has not the same complexity as
disjoint(hashSet, treeSet).
Otherwise, you declare some local variables final.
Declaring a local variable as final doesn't appear in the generated
bytecode.
The usual convention for the source of the JDK is to use final
in front of a local variable only when needed (inner class).
Rémi
PS: I have also CC JSR 166 list mailing list because I know that Doug
Lea also
maintains patches for package java.util.
