KITFORMA · EDITORIAL GUIDE
How do I reject February 30 instead of letting Java adjust an invalid date?
KitForma editorial guide. A parser’s resolving policy can accept, adjust or reject combinations of date fields. A successful parse is only meaningful relative to that policy.
Step-by-step guidance
A parser’s resolving policy can accept, adjust or reject combinations of date fields. A successful parse is only meaningful relative to that policy.
For a strict calendar input, create a formatter with
ofPattern("uuuu-MM-dd").withResolverStyle(ResolverStyle.STRICT) and parse to LocalDate. Catch DateTimeParseException at the input boundary and show a field-level error. Avoid trying several ambiguous patterns until one happens to accept the string.
Test a valid leap day, an invalid leap day, an impossible month and extra trailing input. Use the year symbol appropriate to strict proleptic parsing. This validates a calendar date; business rules such as the allowed delivery range or a minimum age still require separate checks.Sources and verification
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