<i18n dev> RFR: 8358426: Improve lazy computation in Locale

[Johannes Döbler]

On Wed, 4 Jun 2025 21:20:46 GMT, Justin Lu <jlu at openjdk.org> wrote:

> Please review this PR which improves occurrences of lazy computation in `Locale` and `BaseLocale`.
> 
> Existing lazy initialization strategies such as CHM, static nested class, and local inner class are replaced with Stable Values.
> 
> Lambda usage is intentionally avoided in this change during `Locale` creation and in static fields due to potential startup performance degradation as noted by [JDK-8331932](https://bugs.openjdk.org/browse/JDK-8331932).
> 
> Rather than convert `iso3166CodesMap` to a Stable Map, each ISO 3166 resource is represented as a SV. Also, I did not think it was necessary to maintain a SV for _both_ the array and set of ISO3166-1 alpha-2 codes.

src/java.base/share/classes/java/util/Locale.java line 2578:

> 2576:                     return Set.of(LocaleISOData.ISO3166_3);
> 2577:                 }
> 2578:             });

What about moving these four stable suppliers and `getISO2Table` to LocaleISOData to shrink size of Locale.java?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25646#discussion_r2128672698