I'm feeling extremely frustrated.
I copied the source code of Heritrix from the search engine's CD to my machine, and everything else was set up as well. I followed the book step by step for configuration, but Heritrix just wouldn’t start properly. A classmate in the neighboring dorm managed to pass the debugging phase, but he still couldn't get it running either. Moreover, his computer didn’t even have the Apache server installed. Days went by like this, with Heritrix just sitting there unused.
I went online to search for the blog of the author of Heritrix, and in the process, I also resolved my own issues. The following content is hopefully helpful to everyone:
"The Eclipse plugin used in the book can be downloaded from the following address:
http://www.sysdeo.com/sysdeo/eclipse/tomcatplugin.html
or
http://www.sysdeo.com/sysdeo/eclipse/tomcatpluginfr.html"