This article shows how to use the Apache Commons JXPath component to easily query complex Java object trees for data using the XPath expression language. It covers both basic and advanced features ...

Those Java developers, designers, and J2EE architects who work on systems that must store data in relational or object databases, or other storage media should read this article.

However, the Java Platform provides a data structure that greatly simplifies the use of reference objects like this, called the java.util.WeakHashMap class.