RFR: 8342650: Move getChars to DecimalDigits

[j3graham]

On Sun, 20 Oct 2024 00:19:25 GMT, Shaojin Wen <swen at openjdk.org> wrote:

> Move getChars methods of StringLatin1 and StringUTF16 to DecimalDigits to reduce duplication
> 
> 1. HexDigits and OctalDigits also include getCharsLatin1 and getCharsUTF16
> 2. Putting these two methods into DecimalDigits can avoid the need to expose them in JavaLangAccess
> 3. Eliminate duplicate code in BigDecimal

src/java.base/share/classes/java/math/BigDecimal.java line 4216:

> 4214:         // Get the significand as an absolute value
> 4215:         if (intCompact != INFLATED) {
> 4216:             coeff = new char[19];

A possibility here would be to change `coeff` to be a String. The “else” branch already creates a string and has to additionally create a char array from it. If this is the only place where the `DecimalDigits.getChars(… char[])`, some extra code duplication could be removed. The `offset` could then also be removed

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PR Review Comment: https://git.openjdk.org/jdk/pull/21593#discussion_r1807902456