Java LocalDate parse pitfall
If you try to parse a String to a LocalDate with the parse method, you have to be carefull because the default ResolverStyle in the DateTimeFormater, when you call the .ofPattern() method, is SMART.
Sounds funny, it is :).
public enum ResolverStyle {
/**
* Style to resolve dates and times strictly.
* <p>
* Using strict resolution will ensure that all parsed values are within
* the outer range of valid values for the field. Individual fields may
* be further processed for strictness.
* <p>
* For example, resolving year-month and day-of-month in the ISO calendar
* system using strict mode will ensure that the day-of-month is valid
* for the year-month, rejecting invalid values.
*/
STRICT,
/**
* Style to resolve dates and times in a smart, or intelligent, manner.
* <p>
* Using smart resolution will perform the sensible default for each
* field, which may be the same as strict, the same as lenient, or a third
* behavior. Individual fields will interpret this differently.
* <p>
* For example, resolving year-month and day-of-month in the ISO calendar
* system using smart mode will ensure that the day-of-month is from
* 1 to 31, converting any value beyond the last valid day-of-month to be
* the last valid day-of-month.
*/
SMART,
/**
* Style to resolve dates and times leniently.
* <p>
* Using lenient resolution will resolve the values in an appropriate
* lenient manner. Individual fields will interpret this differently.
* <p>
* For example, lenient mode allows the month in the ISO calendar system
* to be outside the range 1 to 12.
* For example, month 15 is treated as being 3 months after month 12.
*/
LENIENT;
}Here are some examples what you should expect:
- LENIENT – Style to resolve dates and times leniently.
2019-02-27 - is parsed to - 2019-02-27
2019-02-28 - is parsed to - 2019-02-28
2019-02-29 - is parsed to - 2019-03-01 //Date moved to next month- SMART – Style to resolve dates and times in a smart, or intelligent, manner.
2019-02-27 - is parsed to - 2019-02-27
2019-02-28 - is parsed to - 2019-02-28
2019-02-29 - is parsed to - 2019-02-28 //Date adjusted based on smart guessing- STRICT – Style to resolve dates and times strictly.
2019-02-27 - is parsed to - 2019-02-27
2019-02-28 - is parsed to - 2019-02-28
2019-02-29 - is parsed to - //java.time.format.DateTimeParseExceptionFor STRICT you have to use [uuuu] instead of [yyyy] for years.