Darryl, Per the SortedSet docs: .....null if this set uses the natural ordering of its elements. Per the NavigableSet.descendingSet docs: "The returned set has an ordering equivalent to Collections.reverseOrder(comparator())" ===================================== NavigableSet<String> fwd = new TreeSet<String>(); NavigableSet<String> rev = fwd.descendingSet(); System.out.println(fwd.comparator() +" "+ rev.comparator()); ===================================== null java.util.Collections$ReverseComparator@4b71bbc9 I don't think the spec allows 'null' to mean reverse natural ordering and natural ordering. Jason
> Date: Tue, 24 Jan 2012 14:18:55 -0800 > From: darryl.mo...@oracle.com > To: jason_mehr...@hotmail.com > CC: core-libs-dev@openjdk.java.net > Subject: Re: Code Review Request Bug #7129185:(coll) Please add > Collections.emptyNavigableSet() > > emptyNavigableSet().descendingSet().comparator() returns null. Isn't > this what's expected? The bounds checking should be correct. > > Darryl