Apache Jakarta Commons: Reusable Java(tm) Components

"Apache Jakarta Commons" shows the reader the power of the Commons libraries. It provides a very brief overview of the available components and goes into detail on 12 of them. APIs are explained through both class diagrams and description. The author provides best practices, warnings and project ideas. The book gets started right away, on page three. The code examples are clear and well commented. The consistent coding standard throughout the book helps with readability. The author highlights differences between the sample code and "real apps." The book is meant for experienced Java programmers. The author assumes readers have knowledge of JSPs, Servlets, Swing and UML. Most importantly, he assumes readers are comfortable with learning by reading through code. Readers are not assumed to have knowledge of the specialized topics such as XPath or encryption. Note that this 325-page book is really a 201-page book. Appendix A is the entire API of the Commons lang project - word for word. I found the printed API to be difficult to read since the methods tend to run into each other. Since the other Commons projects have APIs online only, readers have to be comfortable using the online JavaDoc anyway. This is the type of book that readers will find either valuable or minimally useful. For those who like bound versions, this book gets you started quickly. For those who like online documentation, the UML diagrams are the primary benefit given the online JavaDoc and code samples.

Amazing, the amount of high quality and free software you can get. The latest example is how the open source movement has put together a set of advanced Java classes, that go beyond what the default J2SE SDK gives you. Iverson breaks the Commons offerings into various groupings and explains simple usages of these. Some classes are of quite general utility. As in the Collections, that expand on the Java 2 Collections Framework. The latter is often indispensible for a lot of programming needs. If that describes your situation, the Commons Collections may be worth looking at. The Logging classes should also prove generally useful. Most Commons classes, however, may be more specialised. Those dealing with database connection pooling, for instance. Which is not to say that these and others like them are not useful. Far from it. Just that the needs are specialised. Still, it is probably also worth your while to scan these Commons classes, on the chance that serendipity strikes. Overall, the Commons project is encouraging. More buildout is needed, though.