Stephen Colebourne has released Joda-Time 1.2.1, an open source (Apache license) calendar library. "The design allows for multiple calendar systems, while still providing a simple API. The 'default' calendar is the ISO8601 standard which is used by XML. The Gregorian, Julian, Buddhist, Coptic and Ethiopic systems are also included, and we welcome further additions. Supporting classes include time zone, duration, format and parsing." Java 1.3 or later is suggested. It may or may not work on earlier versions.