The IANA time-zone database [1] provides details of how time-zones change over time. The latest release - 2018f - cannot be processed successfully by the current JDK parser [2]. A workaround exists however unlike previous cases of tzdb incompatibility, this time it makes sense for the JDK parser and API to be changed.
Problem ----------- The JDK parser and API make the assumption that a time-zone change can occur at any LocalTime or midnight-end-of-day, ie. from 00:00 to 24:00. Unfortunately, the tzdb source files allow (and now include) rules outside those valid values, in this case a value of 25:00. Specifically, the rule that causes problems says that clocks change at 25:00 on the first Saturday on or after the 8th of September. In the current problematic case, the rule can be rewritten to say that clocks change at 01:00 on the first Sunday on or after the 9th of September. However, there are cases where it is difficult to impossible to rewrite the rule (such as 25:00 on the last Saturday in a month, difficult because it goes into the next month). Proposed solution ------------------------ Fixing the parser to handle values like 25:00 would be relatively easy. However, these rules are also exposed in the public API of java.time.zone.ZoneOffsetTransitionRule [3]. Currently this class has methods `getLocalTime()` and `isMidnightEndOfDay()`. These would need to be deprecated and replaced by a new method `getLocalTimeDuration()` (or some other name) that returns an instance of `Duration`. A user of ThreeTen-Backport [4] has provided a branch to do this, so I know the change to be possible. However, since I have looked at the code I cannot implement the change in OpenJDK (compromised IP). It needs a cleanroom implementation by someone else. Is there agreement on the need for change? Is anyone (Oracle or otherwise) willing to volunteer do the work? thanks Stephen [1] https://www.iana.org/time-zones [2] https://bugs.openjdk.java.net/browse/JDK-8212684 [3] https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/time/zone/ZoneOffsetTransitionRule.html [4] https://www.threeten.org/threetenbp/
