RFR: 8364007: Add overload without arguments to codePointCount in String etc.

[Chen Liang]

On Thu, 24 Jul 2025 14:50:07 GMT, Tatsunori Uchino <duke at openjdk.org> wrote:

> Adds `codePointCount()` overloads to `String`, `Character`, `(Abstract)StringBuilder`, and `StringBuffer` to make it possible to conveniently retrieve the length of a string as code points without extra boundary checks.
> 
> 
> if (superTremendouslyLongExpressionYieldingAString().codePointCount() > limit) {
>     throw new Exception("exceeding length");
> }
> 
> 
> Is a CSR required to this change?

Also, do we need `codePointCount` on `CharSequence`?

src/java.base/share/classes/java/lang/AbstractStringBuilder.java line 545:

> 543:         byte[] value = this.value;
> 544:         if (isLatin1(coder)) {
> 545:             return value.length;

Suggestion:

            return count;

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PR Review: https://git.openjdk.org/jdk/pull/26461#pullrequestreview-3052346769
PR Review Comment: https://git.openjdk.org/jdk/pull/26461#discussion_r2228974436