garydgregory commented on PR #1532:
URL: https://github.com/apache/commons-lang/pull/1532#issuecomment-3670246510
FTR, this is what Claude Sonet 4.5 says about this change when I generate it
from Eclipse's Co-Pilot plugin using the prompt
>Optimize the method org.apache.commons.lang3.StringUtils.join(boolean[],
char, int, int)
```
Key Optimizations:
1. Fixed Capacity Calculation:
2. Before: Used array.length * 5 + array.length - 1 which incorrectly
calculated based on the full array length
3. After: Uses noOfItems * 6 where noOfItems = endIndex - startIndex,
calculating based on the actual range being joined
4. Benefit: More accurate memory allocation, especially when joining a
subset of the array
5. Eliminated Substring Call:
6. Before: Appended delimiter after every element, then removed the
last delimiter using substring(0, length - 1)
7. After: Appends the first element separately, then appends delimiter
+ element for remaining items
8. Benefit: Eliminates the overhead of creating a substring and copying
characters, improving both performance and memory usage
9. Improved String Builder Usage:
10. Changed from appending element then delimiter to appending
delimiter then element (after the first)
11. Uses toString() instead of substring() which is more efficient
12. Better Capacity Estimation:
13. Uses 6 characters per item estimate (5 for "false" + 1 for
delimiter)
14. More accurate than the previous calculation, reducing StringBuilder
resizing operations
```
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