At your command prompt, type
Sometimes the jvm might default to a version that doesn't work with the supplied code (I don't know why and am not that interested in why). Mine was defaulting to 1.5.0_06 all day, and was annoying me badly until I did the following:
java -version:1.4.2_06 -cp (the rest of the line from the book goes here)
Please note that this is completely different from the CORBA problem that Kathy fixed with the code you can pull off of the wickedlysmart website.