Joda-Time provides a Java library for date and time handling including the ISO8601 standard. It completely replaces the JDK Date and Calendar classes, while still providing good integration. It is open-source software under the ASF2 license.
Version 1.3 has just been released. This release fixes a number of minor bugs in v1.2 but also adds some significant new features:
LocalDate/LocalTime/LocalDateTime
Replacements for YearMonthDay and TimeOfDay which have a much better internal implementation and better external semantics
withXxx() methods
These have been added to all immutable datetime classes and perform a similar function to set methods, simplifying your code
Homepage: http://joda-time.sourceforge.net
Release notes: http://sourceforge.net/project/shownotes.php?release_id=436616&group_id=97367
Download: http://sourceforge.net/project/showfiles.php?group_id=97367&package_id=104212
Hibernate and JSP integration are available from linked websites
Easy to Use - Calendar makes accessing 'normal' dates difficult, due to the lack of simple methods. Joda-Time has straightforward field accessors. And the index of January is 1!
Extensible - Joda-Time supports multiple calendar systems via a plugin mechanism, which is much more extensible than the subclasses of Calendar. Currently supported calendars are ISO8601, GregorianJulian, Buddhist (Thai) Coptic, Ethiopic and Islamic.
Comprehensive - Joda-Time includes classes for datetimes, dates without times, times without dates, intervals and time periods.
Advanced formatting - An advanced and extensible formatting mechanism is included, allowing input and output to string in a thread-safe manner.
Well documented. There is documentation in the form of a quick and full user guide, plus reference pages, FAQs and javadoc.
Tested. There is good test coverage, see the website, providing an assurance of quality.
As always, feedback is welcomed - whether bugs or reviews, good or bad! Only with input from the community can the library improve.
Joda-Time team
http://joda-time.sourceforge.net