This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
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Where did you find this example? It's sure looks wrong. The struts.xml file should be under the WEB-INF directory. Your helloworld.class file should be under classes, not lib. The path is case-sensitive, so I think CLASSES is wrong as well.
If you want a good example, several come with the Struts distribution, including a blank application that you can extend with your own code.