I received an initial phone call from a Comcast recruiter. The recruiter's questions were mostly about career interests, salary expectations, and when I would be available. I then received a call from the hiring manager. There were no technical questions, just questions about what I had on my resume. Next came an on-site interview with two other Senior Software Engineers. One asked almost no technical questions, but the other had put together a list of questions that was about two pages long, mostly pertaining to the Java programming language, APIs, and tools. With about 12 years of Java experience under my belt, I sailed right through these.

I cannot recall a specific question that stood out as being "most difficult or unexpected". However, almost all of the questions could be gleaned from The Java Programming Language or the Java Standard Edition API documentation, for example:

"Describe the java.util.Arrays class."