RFR: 6177299: [Fmt-Nu] NumberFormat.getPercentInstance() does not work correctly [v2]

[Naoto Sato]

On Tue, 30 Sep 2025 17:54:21 GMT, Justin Lu <jlu at openjdk.org> wrote:

>> Please review this PR which corrects an edge case bug for `DecimalFormat` parsing when a multiplier is applied.
>> 
>> This issue applies to any parsed Strings whose resultant double value is rounded to _9.223372036854776E18_ after the multiplier is applied. The returned value is incorrectly given as `Long.MAX_VALUE` when it should be returned as the double _9.223372036854776E18_.
>> 
>> For example, the String _"922,337,203,685,477,600,000%"_ is first parsed as _9.223372036854776E20_, after which the multiplier is then applied to give _9.223372036854776E18_. The original code evaluates `9.223372036854776E18 == (double)(long)9.223372036854776E18` as true, leading to the long representation returned.
>> 
>> The double value should first be checked if it is within the long min/max range before being checked if it can be represented as a long. Note that the check should be inclusive, as during the comparison, `Long.MAX_VALUE` is promoted to _9.223372036854776E18_. Thus _9.223372036854775E18_ correctly compares as false, and all doubles above compare as true.
>
> Justin Lu has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Naoto review - move test to NR.java

Marked as reviewed by naoto (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/27563#pullrequestreview-3286169680