This week's book giveaways are in the Refactoring and Agile forums. We're giving away four copies each of Re-engineering Legacy Software and Docker in Action and have the authors on-line! See this thread and this one for details.
a NullPointerException in an Action class is very common. If you compile your classes with the "-g" option, the stack trace will tell you the actual line number in your code where the error is occurring. The solution is to find the object that's null, find out why it's null, and fix it.
Incidentally, since this is such a generic error, it would have been better if you had included more details: more of the stack trace, indication of when the error occurs, etc. [ March 15, 2007: Message edited by: Merrill Higginson ]