JDK-8342331 : (tz) Update Timezone Data to 2024b
  • Type: CSR
  • Component: core-libs
  • Sub-Component: java.time
  • Priority: P3
  • Status: Closed
  • Resolution: Approved
  • Fix Versions: 8-pool,11-pool,17-pool,21-pool,23-pool
  • Submitted: 2024-10-16
  • Updated: 2024-10-19
  • Resolved: 2024-10-19
Related Reports
CSR :  
JDK-8342297 - (tz) Update Timezone Data to 2024b
Description
Summary
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Updating the TZ Data Base to 2024b in update releases

Problem
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TZdata2024 changes announced on 5th September 2024 includes changes to "EST", "MST", and "HST", i.e., changing those time zones from distinct time zones to links to other time zones. Problem here is, previously they are defined as fixed offset zones, e.g., "EST" is "-05:00" without any DST transitions. With 2024b, "EST" is now a link to "America/Panama." As in the above quote, "America/Panama" has not observed DST since 1970, but offset did change before (i.e., not equal to fixed "-05:00").

This change has Java 8+ specification implications in java.time.ZoneId.SHORT_IDS field, they are explictly defined as fixed zones. Solution for jdk24+ to modify the mappings in ZoneId class which requires modification of the spec.

For update releases, will not make the same ZoneId changes due to current specification. Mappings in ZoneId changes will be made at later in maintenance release for specific versions with the spec changes


Solution
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Override the definitions in 2024b for "EST", "MST", and "HST" with fixed offset ones.

A release note is planned to highlight this issue

Specification
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No specification changes for update releases
Comments
Moving to Approved.
19-10-2024
I believe you can finalize it, without going through the two-pass route.
18-10-2024
Also "interface kind" should not be "Java API" as we don't change it; "compatibility kind" -> behavioral
17-10-2024
I think the solution should mention what the proposed fix would do, i.e., override the definitions in 2024b with fixed offset ones. No need to mention ZoneId spec since we won't change it at all.
17-10-2024