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Commons Collections
Commons-Collections seek to build upon the JDK classes by providing new interfaces, implementations and utilities 

License Apache Software License 
HomePage http://jakarta.apache.org/commons/collections/

Commons Primitives
Apache Jakarta Commons Primitives provides a collection of types and utilities optimized for working with Java primitives (boolean, byte, char, double, float, int, long, short). Generally, the Commons-Primitives classes are smaller, faster and easier to work with than their purely Object based alternatives.

License Apache Software License 
HomePage http://jakarta.apache.org/commons/primitives/

FastUtil
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.

License GNU Library or Lesser General Public License (LGPL) 
HomePage http://fastutil.dsi.unimi.it/

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