Time4J is thought as a complete and high-end replacement for old java classes around java.util.Date, java.util.Calendar and java.text.SimpleDateFormat. This project is also intended as first-class alternative to the popular libraries JodaTime and its successor JSR-310 (Threeten) since the target audience of Time4J will not only be business Java developers, but also developers with a more scientific background (for example extended time scale support including leap seconds or historically accurate dates).
See Git-Repository. The open-source licence is LGPLv2.1. The latest version v2.0 is also available in Maven Central Repository.
API for Time4J-v2.0 (english)