Netlib is a collection of mission-critical software components for linear algebra systems (i.e. working with vectors or matrices). Netlib libraries are written in C, Fortran or optimised assembly code. A Java translation has been provided by the F2J project but it does not take advantage of optimised system libraries.
fastutil extends the Java™ Collections Framework by providing type-specific maps, sets, lists and queues with a small memory footprint and fast access and insertion; it also includes a fast I/O API for binary and text files. It is free software distributed under the GNU Lesser General Public License.