Collections and utilities based on primitives types
Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more.
jin collections is a tool libraries that help working with standard Java Collections utility in a "Code by Intenction" way. It is inspired from Smalltalk Collections Utility.
Trove of primitive collections with Apache 2.0 license, built for Java Java 6 or 7
Functional extension of google collections
Trove of primitive collections with Apache 2.0 license, built for Java Java 8
It is the framework of lazy collections based on Iterator and Iterable interfaces
Library providing immutable/persistent collection classes for Java. While collections are immutable they provide methods for adding and removing values by creating new modified copies of themselves. Each copy shares almost all of its structure with other copies to minimize memory consumption.
Custom Collection Implementations