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2024.3

String concatenation in loop

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Last modified: 03 December 2024

Reports String concatenation in loops.

As every String concatenation copies the whole string, usually it is preferable to replace it with explicit calls to StringBuilder.append() or StringBuffer.append().

Example:

After the quick-fix is applied:

Sometimes, the quick-fixes allow you to convert a String variable to a StringBuilder or introduce a new StringBuilder. Be careful if the original code specially handles the null value, as the replacement may change semantics. If null is possible, null-safe fixes that generate necessary null-checks are suggested. Also, it's not guaranteed that the automatic replacement will always be more performant.