Summary

By using the Logging package, robust configurable logging can be added to your applications. Depending on your needs, this can be used to debug your application while under development, to debug your application in production, to record performance information, or even as a mechanism for generating access or other usage log files.

Logging is an example of a function that is commonly used across a wide variety of applications. In the next chapter, an even more general set of commonly used utilities will be presented.

Project Ideas

Use the Logging interface to build an application that generates a wide variety of log data. Compare the performance, configurability, and details provided by log4j to the default Java logging implementation. How do various types of logging affect application performance?

Write a tool, perhaps using SAX, DOM, XSLT, or JDOM, to process large XML log files. What sort of useful metrics can be generated, perhaps as a summary HTML document?