Apache Commons - Apache Commons
Apache Commons is an Apache project focused on all aspects of reusable Java components. The Apache Commons project is composed of three parts: You may also read our charter, which spells out the goals of the project in greater detail. The Apache Commons source code repositories are writable for all ASF committers.
Collections - Home
The Java Collections Framework was a major addition in JDK 1.2. It added many powerful data structures that accelerate development of most significant Java applications. Since that time it has become the recognised standard for collection handling in Java. Commons-Collections seek to build upon the JDK classes by providing new interfaces, implementations and utilities.