RFR: 8316426: Optimization for HexFormat.formatHex

[温绍锦]

On Mon, 18 Sep 2023 19:08:14 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> src/java.base/share/classes/java/util/HexFormat.java line 422:
>> 
>>> 420:                         toHexDigits(out, bytes[fromIndex + i]);
>>> 421:                     }
>>> 422:                     out.append(suffix);
>> 
>> Maybe change this whole `else` block to
>> 
>>                     for (int i = 0; i < length; i++) {
>>                         if (i > 0)
>>                             out.append(delimiter);
>>                         out.append(prefix);
>>                         toHexDigits(out, bytes[fromIndex + i]);
>>                         out.append(suffix);
>>                     }
>> 
>> for clarity?
>
> The original (and current) is coded to avoid a condition inside the loop.

I also think that the way of writing for_0 combined with if > 0 is easier to understand, The operation overhead of if > 0 is very small, and it will not affect performance when used in a loop.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/15768#discussion_r1329453524