Case Conversion Chained With equals()
ID |
java.locale_case_then_equals |
Severity |
low |
Remediation Complexity |
trivial |
Remediation Risk |
low |
Remediation Effort |
low |
Resource |
Reliability |
Language |
Java |
Tags |
best-practice, reliability |
Description
Reports chained calls like s.toUpperCase().equals("FOO") or s.toLowerCase().equals("bar"), as well as the reversed form "FOO".equals(s.toUpperCase()). These patterns should use equalsIgnoreCase() instead, which is both more efficient and locale-safe.
Rationale
toUpperCase() and toLowerCase() are locale-sensitive. In the Turkish locale, for example, 'i'.toUpperCase() produces a dotted capital I ('\u0130'), not 'I'. This means s.toUpperCase().equals("FOO") can give different results depending on the JVM’s default locale, leading to subtle, hard-to-reproduce bugs.
Additionally, toUpperCase() creates a new String object that is used only for the comparison and then discarded, wasting memory.
// Bad -- locale-dependent and creates intermediate String
if (s.toUpperCase().equals("FOO")) { ... }
if ("foo".equals(s.toLowerCase())) { ... }Remediation
Use equalsIgnoreCase() which handles case-insensitive comparison correctly across all locales.
// Good -- locale-safe and no intermediate String
if (s.equalsIgnoreCase("FOO")) { ... }