Proj4J is a Java library to transform point coordinates from one geographic coordinate system to another, including datum transformations.
The core of this library is a port of the PROJ.4 C library. The projection algorithms, concepts and coordinate system definitions are all taken directly from PROJ.4. These are wrapped in a Java class model which follows standard Java conventions and OO best practices.
Proj4J is a part of the MetaCRS group of projects, hosted by OSGeo.
The PROJ.4 documentation is the best reference for details of the coordinate system specification language, projection algorithms and supported parameters.
the [Version History](doc/Proj4J Version History.html) lists the evolution of features of the library
the Javadoc describes the API
A mailing list is available for users and developers of Proj4J.
Subscription, unsubscription and a web archive are at http://lists.osgeo.org/mailman/listinfo/proj4j.
Direct link to the mailing list archive.
SVN repository: http://svn.osgeo.org/metacrs/proj4j.
Browse source here.
Submit a new bug report (you need to login with an OSGeo Userid)
Proj4J is licensed under the Apache License, Version 2.0.
The Proj4J codebase is based on a partial port of PROJ.4 carried out by JHLabs circa 2006. The JHLabs port provided a large number of the PROJ.4 projections, but did not support some PROJ.4 features such as datum transformation.