guava

Guava: Google Core Libraries for Java 1.6+

The Guava project contains several of Google's core libraries that we rely on in our Java-based projects: collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and so forth.

http://code.google.com/p/guava-libraries/

http://code.google.com/p/guava-libraries/wiki/GuavaExplained

Maven

   1 <dependency>
   2     <groupId>com.google.guava</groupId>
   3     <artifactId>guava</artifactId>
   4     <version>12.0</version>
   5 </dependency>

Cache

http://code.google.com/p/guava-libraries/wiki/CachesExplained