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This is a very large book, coming in at 1200 pages, but that is because it is the author's 815 and 816/817 books combined. The authors highlighted how to use the book to study for the 815, 816 or 817 exams, so it is easy to use, but if it's too much for you, they are also sold separately.
I'm not finished with the book yet, but I like what I read so far. I started by looking at the security chapter. I really liked that Hacker Harry and Security Sienna characters were used to teach security. It made what could have been a dry chapter a lot more fun.
If you are taking a Java certification, I highly recommend this combined book or the two separate ones.
I believe that this book is still the only one to cover the 1Z0-816 material, and they do an excellent job. The only other source I have found for the 816 topics is Tim Bulchaka's course on Udemy. The rendition of the eBook in Kindle is flawless.