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TimurMahammadov / google-collections

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should there be an Objects.compare(@Nullable Comparable c1, @Nullable Comparable c2) method? #103

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
Just like Objects.equals() dealing with nulls but for compareTo?

Original issue reported on code.google.com by james.st...@gmail.com on 31 Oct 2008 at 7:28

GoogleCodeExporter commented 9 years ago 
Hi, James.  To implement this method, of course, we need to decide whether 
nulls are
less than all objects or greater than all objects.  We'd probably end up with
Objects.compareNullGreatest() and Objects.compareNullLeast() to let the caller
choose.  It also makes sense to go from a static compare() method to a 
Comparator to
allow use as a Collection ordering, etc.  In fact, in the Comparators class, we 
have
nullGreatestOrder() and nullLeastOrder().  Calling 
nullGreatestOrder().compare(c1,
c2) or nullLeastOrder().compare(c1, c2) should do what you want.

Original comment by cpov...@google.com on 31 Oct 2008 at 2:34

GoogleCodeExporter commented 9 years ago 
Aha thats cool - sorry I'd missed those! Many thanks!

I wonder if its worth adding a couple of trivial static helper methods so its 
easier for folks to find these helper 
methods more easily? e.g. if I have 2 comparables I could just do

{{{
  boolean Comparables.compareNullGreatest(c1, c2);
  boolean Comparables.compareNullLeast(c1, c2);
}}}

Am used to finding the static methods by typing HelperClass.X (where X is the 
first character of the method 
(new/equals/compare etc) so it'd make it a tad easier for folks to find these 
methods in IDEs. 

Not a huge biggie though. I'd just never thought of searching for all methods 
in Comparables. that starts with 
"n" for null :)

Original comment by james.st...@gmail.com on 31 Oct 2008 at 2:47

GoogleCodeExporter commented 9 years ago 
I don't think null-friendly comparison is done on the same on the order of 
magnitude
as null-friendly equality and null-friendly hashing are, so I don't think this
warrants adding.

Original comment by kevin...@gmail.com on 31 Oct 2008 at 4:29

GoogleCodeExporter commented 9 years ago 
I was looking for it some time ago.

Original comment by earwin@gmail.com on 3 Nov 2008 at 9:57

GoogleCodeExporter commented 9 years ago

Original comment by kevin...@gmail.com on 29 Dec 2008 at 8:38