[threeten-dev] jdk bug in OffsetDateTime.INSTANT_COMPARATOR

[Patrick Zhang]

Hi Team,

It looks one bug in java.time.OffsetDateTime. The return value of 
compareTo() and OffsetDateTime.INSTANT_COMPARATOR.compare() are different.
Sample code:
========
OffsetDateTime a = OffsetDateTime.of(2008, 6, 30, 11, 20, 40, 4, 
ZoneOffset.ofHours(2));
OffsetDateTime b = OffsetDateTime.of(2008, 6, 30, 10, 20, 40, 5, 
ZoneOffset.ofHours(1));
System.out.println(a.compareTo(b));
System.out.println(OffsetDateTime.INSTANT_COMPARATOR.compare(a, b));
========

Output:
========
-1
1
========

I do not think it makes sense. The correct value should be a<b.

  And it looks the implementation of INSTANT_COMPARATOR is incorrect:
=========
     public static final Comparator<OffsetDateTime> INSTANT_COMPARATOR = 
new Comparator<OffsetDateTime>() {
         @Override
         public int compare(OffsetDateTime datetime1, OffsetDateTime 
datetime2) {
             int cmp = Long.compare(datetime1.toEpochSecond(), 
datetime2.toEpochSecond());
             if (cmp == 0) {
                 cmp = 
Long.compare(datetime1.toLocalTime().toNanoOfDay(), 
datetime2.toLocalTime().toNanoOfDay());
             }
             return cmp;
         }
     };
=========

I think we can not compare localTime part of OffsetDateTime directly.
It should be convert to Instant firstly. Then compare epochSecond and 
nanoOfSecond.....

Regards
Patrick