Parse date-only as LocalDateTime in Java 8

Question

I need to parse a field which is sometimes given as a date and sometimes as a date/time. Is it possible to use single datatype for this using Java 8 time API? Currently, I a

Answer 1

Just create custom formatter with the builder DateTimeFormatterBuilder

DateTimeFormatter formatter = new DateTimeFormatterBuilder()
        .appendPattern("yyyy-MM-dd[ HH:mm:ss]")
        .parseDefaulting(ChronoField.HOUR_OF_DAY, 0)
        .parseDefaulting(ChronoField.MINUTE_OF_HOUR, 0)
        .parseDefaulting(ChronoField.SECOND_OF_MINUTE, 0)
        .toFormatter();

This formatter uses the [] brackets to allow optional parts in the format, and adds the default values for hour HOUR_OF_DAY, minute MINUTE_OF_HOUR and second SECOND_OF_MINUTE.

note: you can ommit, minutes and seconds, just providing the hour is enough.

And use it as usual.

LocalDateTime localDateTime1 = LocalDateTime.parse("1994-05-13", formatter);
LocalDateTime localDateTime2 = LocalDateTime.parse("1994-05-13 23:00:00", formatter);

This outputs the correct date time with default hours of 0 (starting of the day).

System.out.println(localDateTime1); // 1994-05-13T00:00
System.out.println(localDateTime2); // 1994-05-13T23:00