<i18n dev> RFR: 8247781: Day periods support [v5]

[Joe Wang]

On Fri, 30 Oct 2020 11:42:49 GMT, Stephen Colebourne <scolebourne at openjdk.org> wrote:

>> Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fixed TCK test failures, added the new pattern char description in DateTimeFormatter
>
> Changes requested by scolebourne (Author).

Since 24:00 is not represented in for example LocalTime and H (hour-of-day) 0-23, it seems obvious midnight in the JDK would be 00:00, and the new DayPeriod tests proves that. The CLDR rule for midnight is also obvious, but the LDML spec does state that it "strongly recommend" that implementations provide for the ability to specify whether midnight is supported or not (and for either 00:00 or 24:00 or both). 

Just wonder whether there is a need to explicitly state the fact about midnight? DateTimeFormatterBuilder::appendInstant() for example, stated clearly how 24:00 is processed, e.g. "The end-of-day time of '24:00' is handled as midnight at the start of the following day."

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PR: https://git.openjdk.java.net/jdk/pull/938