An equals method should always be consistent in its definition. Having
the chronology sometimes used and sometimes not would not be good.
All Joda-Time objects (and all imutable objects in general) should
have an equals method that is based on the entire state of the object
- and clearly the chronologies are different. They should also have a
toString exposing the entire state of the object, but sadly that isn't
the case.
If you want to compare two dates for date-on-time-line, use isEqual().
Stephen
On 28 June 2012 18:51, John Hanks <jhanks9...@gmail.com> wrote:
> In my example I had have 2 LocalDates.
>
> They both have the same toString() output: 2012-06-21
>
> One uses GJChronology and the other ISOChronology.
>
> Since the date "2012-06-21" represents the same time in both chronologies,
> why can't the equals() method return true for that date?
>
>
> On Thu, Jun 28, 2012 at 1:02 AM, Stephen Colebourne <scolebou...@joda.org>
> wrote:
>>
>> 2012-05-01 in ISO and 2012-05-01 in Coptic/Ethiopic/Hijra etc are
>> totally different dates on the time-line. You're only considering it
>> to be a problem because for GJ after the cutover date they happen to
>> represent the same date on the time-line.
>>
>> Its a design flaw, because pluggable chronologies don't work for most
>> people as they don't realise the chronology field exists and is used
>> in most cases. The problem is made worse because the toString doesn't
>> show it. But there is zero chance of fixing it. Its not a bug, because
>> it works as originally intended and designed, its just that the design
>> is imperfect (and backwards compatibiilty prevents change).
>>
>> ThreeTen/JSR-310 will have a different design approach, because of this
>> issue.
>>
>> The short answer is that you must control the chronology of the
>> dates/times you use.
>>
>> Stephen
>>
>>
>> On 28 June 2012 01:51, John Hanks <jhanks9...@gmail.com> wrote:
>> > I agree that comparing chronology in the equals() method for the
>> > LocalDate
>> > class is a design flaw (bug).
>> >
>> > Are there any plans on fixing it?
>> >
>> > I can see some pretty nasty bugs from this such as using LocalDate
>> > instances
>> > as keys in a Map. You might not get what you expect.
>> >
>> > On Wed, Jun 27, 2012 at 2:15 AM, Stephen Colebourne
>> > <scolebou...@joda.org>
>> > wrote:
>> >>
>> >> Print out the result of getChronology() for both, and see if they are
>> >> equal. I suspect they are different (equals depends on the chronology
>> >> - a design flaw in Joda-Time).
>> >> Stephen
>> >>
>> >>
>> >>
>> >> On 27 June 2012 02:51, John Hanks <jhanks9...@gmail.com> wrote:
>> >> > I was surprised when I was using the equals() method of the LocalDate
>> >> > class.
>> >> >
>> >> > It was not behaving as I would expect.
>> >> >
>> >> > Take a look at the code below:
>> >> >
>> >> > DateTimeFormatter dateTimeFormat =
>> >> > DateTimeFormat.forPattern("yyyyMMdd
>> >> > HH:mm");
>> >> > Calendar calendar = dateTimeFormat.parseDateTime("20120621
>> >> > 09:00").toCalendar(null);
>> >> > LocalDate localDate1 = new LocalDate(calendar);
>> >> > LocalDate localDate2 = new LocalDate(2012,6,21);
>> >> > System.out.println(localDate1);
>> >> > System.out.println(localDate2);
>> >> > System.out.println("equals(): " +
>> >> > localDate1.equals(localDate2));
>> >> > System.out.println("isEqual(): " +
>> >> > localDate1.isEqual(localDate2));
>> >> >
>> >> >
>> >> > The output is:
>> >> >
>> >> > 2012-06-21
>> >> > 2012-06-21
>> >> > equals(): false
>> >> > isEqual(): true
>> >> >
>> >> >
>> >> > Why is the equals method comparison false.
>> >> >
>> >> > Is this not a Joda bug?
>> >> >
>> >> > P.S. I'm using Joda 2.1
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
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