JTS Topology Suite

 JTS is a java library which provides:
  * an implementation of the spatial data model defined
    in the OGC Simple Features Specification for SQL (SFS)
  * a complete, consistent, implementation of fundamental 2D spatial algorithms
  * an explicit precision model, with algorithms that gracefully handle
    situations that result in dimensional collapse
  * robust implementations of key computational geometric operations
  * I/O in Well-Known Text format