Quite an old article on JavaWorld: "As part of the Java language, the java.lang package is implicitly imported into every Java program. This package's pitfalls surface often, affecting most programmers. This month, I'll discuss the traps lurking in the Runtime.exec() method."
Exception Handling with Spring and Log4J
How to log exceptions. This technique will log messages to your server log file, send an email, with the tag stack of the error, for error level warnings and display a generic page to the user.
First step is to set up Log4j.
Make sure you have the following classes in application lib or common server lib.
activation.jar
This can be got from http://java.sun.com/products/javabeans/jaf/downloads/index.html
Set up your log4J configuration file, put this file in your WEB-INF directory