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Chapter 3. Red Hat build of OpenJDK features

The latest Red Hat build of OpenJDK 21 release might include new features. Additionally, the latest release might enhance, deprecate, or remove features that originated from earlier Red Hat build of OpenJDK 21 releases.

Note

For all the other changes and security fixes, see OpenJDK 21.0.6 Released.

Red Hat build of OpenJDK enhancements

Red Hat build of OpenJDK 21 provides enhancements to features originally created in earlier releases of Red Hat build of OpenJDK.

Option for jar command to avoid overwriting files when extracting an archive

In earlier Red Hat build of OpenJDK releases, when the jar tool extracted files from an archive, the jar tool overwrote any existing files with the same name in the target directory.

Red Hat build of OpenJDK 21.0.6 adds a new ‑k (or ‑‑keep-old-files) option that you can use to ensure that the jar tool does not overwrite existing files. You can specify this new option in either short or long format.

For example:

  • jar xkf myfile.jar
  • jar --extract ‑‑keep-old-files ‑‑file myfile.jar
Note

In Red Hat build of OpenJDK 21.0.6, the jar tool retains the old behavior by default. If you do not explicitly specify the ‑k (or ‑‑keep-old-files) option, the jar tool automatically overwrites any existing files with the same name.

See JDK-8335912 (JDK Bug System) and JDK bug system reference ID: JDK-8337499.

IANA time zone database updated to version 2024b

In Red Hat build of OpenJDK 21.0.6, the in-tree copy of the Internet Assigned Numbers Authority (IANA) time zone database is updated to version 2024b. This update is primarily concerned with improving historical data for Mexico, Mongolia, and Portugal.

This update to the IANA database also includes the following changes:

  • Asia/Choibalsan is an alias for Asia/Ulaanbaatar.
  • The Middle European Time (MET) time zone is equal to Central European Time (CET).

  • Some legacy time-zone IDs are mapped to geographical names rather than fixed offsets:

    • Eastern Standard Time (EST) is mapped to America/Panama rather than -5:00.
    • Mountain Standard Time (MST) is mapped to America/Phoenix rather than -7:00.
    • Hawaii Standard Time (HST) is mapped to Pacific/Honolulu rather than -10:00.

    Red Hat build of OpenJDK overrides the change in the legacy time-zone ID mappings by retaining the existing fixed-offset mapping.

See JDK-8339637 (JDK Bug System).

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