Mcgill,
Based on chapter one (downloadable from the manning site), the book assumes a working knowledge of basic java. It assumes you know about inheritance, interfaces, exceptions, private/public, ...
Ali,
I've found that the Mannings books don't assume you know anything about the topic (in this case reflection), but they do assume you know about other things. For example, the
JUnit in Action book also assumes a working knowledge of basic java. Which makes sense because these aren't intro to java books.