RFR: 8357289: Break down the String constructor into smaller methods [v3]

[Shaojin Wen]

On Sun, 25 May 2025 04:39:24 GMT, Chen Liang <liach at openjdk.org> wrote:

>> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   create method share variant val & coder
>
> src/java.base/share/classes/java/lang/String.java line 703:
> 
>> 701:                 throw new Error(x);
>> 702:             }
>> 703:             if (COMPACT_STRINGS) {
> 
> Now we can call other constructors of String, so instead of having this manual handling of char[], we can call `return new String(ca, 0, caLen, null)`. Same for the `clen` version above.

private String(char[] value, int off, int len, Void sig) {
        if (len == 0) {
            this.value = "".value;
            this.coder = "".coder;
            return;
        }
        if (COMPACT_STRINGS) {
            byte[] val = StringUTF16.compress(value, off, len);
            this.coder = StringUTF16.coderFromArrayLen(val, len);
            this.value = val;
            return;
        }
        this.coder = UTF16;
        this.value = StringUTF16.toBytes(value, off, len);
    }


This constructor has additional processing logic for len == 0. 

ValueObject may be used here in the future. I think it is better to keep the original structure.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25290#discussion_r2106099679