JoSQL (SQL for Java Objects) provides the ability for a developer to apply a SQL statement to a collection of Java Objects. JoSQL provides the ability to search, order and group ANY Java objects and should be applied when you want to perform SQL-like queries on a collection of Java Objects.
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http://commons.apache.org/jxpath/
The org.apache.commons.jxpath package defines a simple interpreter of an expression language called XPath. JXPath applies XPath expressions to graphs of objects of all kinds: JavaBeans, Maps, Servlet contexts, DOM etc, including mixtures thereof.