Collections

The Apache Commons Collections package contains types that extend and augment the Java Collections Framework.

Eclipse Collections API

MapDB provides concurrent Maps, Sets and Queues backed by disk storage or off-heap memory. It is a fast, scalable and easy to use embedded Java database.

fastutil extends the Java Collections Framework by providing type-specific maps, sets, lists and priority queues with a small memory footprint and fast access and insertion; provides also big (64-bit) arrays, sets and lists, sorting algorithms, and fast, practical I/O classes for binary and text files.

Types that extend and augment the Java Collections Framework.

The Trove library provides high speed regular and primitive collections for Java.

A high performance version of java.util.LinkedHashMap for use as a software cache.

Google Collections Library is a suite of new collections and collection-related goodness for Java 5.0

Highly Scalable Java

High Performance Primitive Collections: data structures (maps, sets, lists, stacks, queues) generated for combinations of object and primitive types to conserve JVM memory and speed up execution.