[threeten-dev] ISO8601 durations and java.time

[Stephen Colebourne]

Originally, the Period class handled all units from years to nanos. We
chose to simplify it to just being date-based. Most real use cases are
date based or time based, and it becomes more difficult to explain the
rationale behind the class relative to Duration if it includes all
units. Plus, Period is now a lot smaller and easier to understand,
especially wrt normalization.

It would be perfectly possible to write a combined class, either
backed by Duration and Period or standalone. The TemporalAmount
interface permits such a thing.

Oracle have not currently indicated a desire to integrate with the XML
Duration class.

Stephen



On 12 September 2013 11:21, Klaus Malorny <Klaus.Malorny at knipp.de> wrote:
> recently I took a first look on the new API that comes with Java 8 and
> discovered something that puzzles me, namely, that there does not seem to
> exist a class that can fully represent ISO8601 durations. "Duration" does
> not understand months and years, while "Period" does not understand hours,
> minutes and seconds/fractions. I have read somewhere about a distinction
> between a "human" and a "machine" time line, and for the latter, it may make
> sense for not having months and years, but not for the other for not
> supporting durations below a day.
>
> I consider not having a class representing ISO8601 durations as problematic,
> as these appear here and there in the real world, for example in XML
> schemas* or in databases (e.g. PostgreSQL supports something like). One
> would have to manage this as a pair of Duration and Period, and would need
> to have a custom parser and string conversion. But maybe I simply
> misunderstand the API. I looked into the mailing list archive for the recent
> months, but I did not find any discussion about it, so I just joined the
> mailing list to ask about.
>
> Regards,
>
> Klaus
>
>
> * I also cannot see any interaction of the new API with the
> javax.xml.datatype.Duration class