Newbie question regarding Selenium

I just started learning Selenium, and would like to try a simple example.

However, I get the following exceptio开发者_Go百科n when I run the code:

Exception in thread "main" java.lang.NoClassDefFoundError: com/gargoylesoftware/htmlunit/WebWindowListener

Does anyone know how to mitigate this?

Thank you.

NewbieIntern solved this issue himself, but, I'll put in this answer so people on Google are happy.

You have to include the selenium server jar or, in NewbieIntern's words, "selenium-server-standalone-2.0a5.jar". This version number will probably change.