Implements some ideas from NuPIC in Java, with an eye toward high performance (colocated data, flyweight objects).
What has tests works, and the general design is sound. I wrote this in the summer of 2013, with plans on getting back to it, but haven't found the time. Since NuPIC is now doing a Java implementation, I'm making this available under a compatible license in case it is useful there (at least for inspiration).
License is GPL v3.