<i18n dev> [9] RFR: 8048123: Replace calendars.properties with another mechanism to specify a new Japanese calendar era

Masayoshi Okutsu masayoshi.okutsu at oracle.com
Tue Jul 22 16:14:49 UTC 2014

You are right. Those could happen in theory. As far as I checked, there 
are two eras which are shorter than one year, 朱鳥 in 686 (Julius) and 
天平感宝 in 749 (Julius). Both have only a few months. So I wouldn't say 
it's quite a risk, especially under the current rule, one era per emperor.

One issue is that the current Japanese calendar implementation isn't 
ready for such extreme cases, like a one-day year which breaks some 
assumptions. Currently, java.time uses the j.u.JapaneseImperialCalendar 
implementation. So java.time has the same restrictions. You may want to 
implement the perfect Japanese calendar which supports all the past eras 
(with all the different transition rules) and all the possible future 
era transitions.


On 7/22/2014 10:33 PM, Stephen Colebourne wrote:
> A Japanese Emperor might only reign for one day or one week, which is
> far less time than a JDK update. It seems to me that one additional
> era is quite a risk to be baking into the JDK.
> Stephen
> On 22 July 2014 09:05, Masayoshi Okutsu <masayoshi.okutsu at oracle.com> wrote:
>> The assumption here is that it's enough to support one additional era until
>> the era is added to the built-in eras in update releases.
>> Masayoshi
>> On 7/22/2014 4:52 PM, Stephen Colebourne wrote:
>>> It seems that the system property only supports one additional era.
>>> Given that Japanese eras are based on human lifetimes, that seems an
>>> invalid assumption.
>>> Stephen
>>> On 22 July 2014 08:06, Masayoshi Okutsu <masayoshi.okutsu at oracle.com>
>>> wrote:
>>>> Hello,
>>>> Please review the change for JDK-8048123. This change removes all the era
>>>> definitions in ${java.home}/lib/calendars.properties. (The property file
>>>> will eventually be gone later.) The major change is that any new era of
>>>> the
>>>> Japanese calendar should now be defined using new property
>>>> "jdk.calendar.japanese.supplemental.era".
>>>> https://bugs.openjdk.java.net/browse/JDK-8048123
>>>> Webrev includes some unrelated cleanups.
>>>> http://cr.openjdk.java.net/~okutsu/9/8048123/webrev.00/
>>>> Thanks,
>>>> Masayoshi

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