RFR: 8365832: Optimize FloatingDecimal and DigitList with byte[] and cleanup [v6]

[Chen Liang]

On Wed, 20 Aug 2025 15:41:25 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> Since FloatToDecimal and DoubleToDecimal are used in Float.toString and Double.toString, some code in FloatingDecimal is not used. 
>> 
>> This PR refactors `FloatingDecimal` and `DigitList` to improve efficiency and reduce code duplication.
>> 
>> Key changes:
>> * Convert internal digit storage from `char[]` to `byte[]` for reduced memory footprint.
>> *   Remove unused code and methods that are no longer needed.
>
> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   without copy digits, from @j3graham

src/java.base/share/classes/jdk/internal/math/FloatingDecimal.java line 105:

> 103:      */
> 104:     public interface BinaryToASCIIConverter {
> 105:         int getChars(byte[] result);

Can you add javadoc comments to this new method, like what is the return value, and any caution for the size of the result array before passing etc.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23311#discussion_r2291159227