RFR: 8368328: CompactNumberFormat.clone does not produce independent instances

[Justin Lu]

On Wed, 24 Sep 2025 17:37:59 GMT, Naoto Sato <naoto at openjdk.org> wrote:

> Fixing `CompactNumberFormat.clone()` to clone mutable reference objects. The bug was caused by accessing the shared objects concurrently which resulted in an illegal state on parsing. There are other reference fields that are shared, but the contents of those fields (such as prefix/suffix) are constants/read-only, so they may be shared.

test/jdk/java/text/Format/CompactNumberFormat/TestClone.java line 62:

> 60:                     } catch (ParseException pe) {
> 61:                         throw new RuntimeException(pe);
> 62:                     }

Can replace the try/catch with 
`assertDoesNotThrow(() -> assertEquals(num, clone.parse(String.valueOf(num)).intValue()));`

test/jdk/java/text/Format/CompactNumberFormat/TestClone.java line 77:

> 75:     private static Stream<Arguments> referenceFields() throws ClassNotFoundException {
> 76:         return Stream.of(
> 77:             Arguments.of("decimalFormat", DecimalFormat.class),

We should also include `Arguments.of("symbols", DecimalFormatSymbols.class)` as an entry.

test/jdk/java/text/Format/CompactNumberFormat/TestClone.java line 87:

> 85:     @MethodSource("referenceFields")
> 86:     void whiteBoxTest(String fieldName, Class<?> type) throws Throwable {
> 87:         var original= NumberFormat.getCompactNumberInstance(Locale.US, NumberFormat.Style.SHORT);

Suggestion:

        var original = NumberFormat.getCompactNumberInstance(Locale.US, NumberFormat.Style.SHORT);

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PR Review Comment: https://git.openjdk.org/jdk/pull/27475#discussion_r2377012157
PR Review Comment: https://git.openjdk.org/jdk/pull/27475#discussion_r2377017033
PR Review Comment: https://git.openjdk.org/jdk/pull/27475#discussion_r2377018396