When a virtual thread runs blocking code, which is code that forces threads to wait until an operation completes -- for example, executing an HTTP request to a web server -- the Continuation object ...

The main thread is a good example of a non-daemon thread. Code in main() will be always be executed until the end, unless a System.exit() forces the program to complete.

All in all, this is a good book — just not your typical presentation of Java threads. As far as the book’s examples go, watch out for Elvis getting caught by the UFOs.