Java library to support dates with limited precision (like year/month only)

Question

In some system I have to operate on dates which may have limited precission (like month and year only or year only), e.g. "2001" or "January 2011". I need to know not only date, but the presission (day, month or year) as well.

I can do this by hand, but does anybody know any java library which supports this type of dates with variable precission?

Sechrist

Answer 1

I would consider using a well known library such as Joda Time and model each "date" as a time span (Interval in Joda Time).

After all, that's sort of what it is; "2001" is not actually a specific point in time, but a period.

The span / length of the interval would reveal the precision, and the starting point of the period could be interpreted as the point in time at which the "date occurred".

Arthromere

It's not a period in the Joda sense ("2 months" or "3 week") - it's a partial, like YearMonth, LocalDate etc. – Agretha

Aha. Not very experienced with the library. Thanks for clearing it up. – Arthromere

Answer 2

java.time

In modern Java, use java.time classes defined in JSR 310, built into Java 8+.

Never use Date, Calendar, SimpleDateFormat, etc. Those terribly-flawed classes outside of the java.time package are legacy.

YearMonth

like month and year only

Use java.time.YearMonth. Construct with your choice of month number or Month enum.

YearMonth ym = YearMonth.of( 2025 , Month.JUNE ) ;

Year

or year only

Use java.time.Year.

Year y = Year.of( 2025 ) ;

LocalDate

not only date

For date-only, use LocalDate. No time-of-day, no time zone nor offset.

LocalDate ld = LocalDate.of( 2025 , Month.NOVEMBER , 17 ) ;

Pandich

Answer 3

Lookup SimpleDateFormat and Date. These both classes should be sufficient for your use case.

Reference: SimpleDateFormat

Shirline

Yep, but this is what I mean by 'by hand' - create class which has precision and date, and define all operations, using Calendar/Date/SimpleDateFormat. But before start I wanted to check - maybe someone did it already, and there is a good standard solution? – Sechrist

Answer 4

Use Joda Time which already has support for a YearMonth type (amongst other things) - you can create your own Year type if you want, based on similar code.

Agretha