I've been reading the RHE study guide for certification, and looking back over some of my completed CattleDrive assignments for examples here and there. I notice in the instructor's solution for one assignment (changed here slightly to protect future students) that he starts with a class within a class, BOTH of which are declared public, as in:
How does this fit with the following statement from RHE:
There may be AT MOST ONE PUBLIC class definition per source file...." (emphasis added)
I think RHE is implying that there may be at most one public top-level class definition per source file...(bold added for emphasis) In your example, the second public class is an inner class. -Peter Ps. You may want to submit to RHE a suggestion to make this explicit in their next edition.