Fastutil - Fast & compact type-specific collections for Java

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 provides also big (64-bit) arrays, sets and lists, and fast, practical I/O classes for binary and text files.

It has support of bidirectional iterators. It has support of Big arrays and Big Lists with 64 Bit indices.