Volume I gets readers who are experienced programmers in some language up to speed in Java. Volume II is intended for experienced Java developers. It covers advanced API and language features. While few readers will need all the advanced topics, most of them should have broad appeal to an advanced audience.
Both books stick to the core Java language and APIs.
The Thread class exposes a number of properties for threads, but most of them are more useful for students of certification exams than application programmers.
That was from your Impatient Java9 book, page 366, §10.8.4.
That tells me that you think application programmers are more impatient than cert exam candidates (), and gives me a hint that you probably intended the book for application programmers rather than cert exam students.
By the way: Have you written a beginner's book with “Impatient” in its title, or am I getting confused?
posted 1 week ago
The "Impatient" books also assume that the reader is an experienced programmer in some language. They just don't go into the same exhaustive depth as Core Java. In particular, they only cover the latest features without tracing the history. For example, in Core Java for the Impatient, I never mention java.io.File because java.nio.file.Path is a better choice. In Core Java, I cover both and tell the reader to use Path when they can.
And as for certification students, I hope they are patient people. There is a lot of trivia in those exams, not at all reflective of what a good application programmer should know. I don't really know how to prepare for one, but if I had to, I'd want to first read a good book about the topic to understand it well, and then turn to an exam cram book.