This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
Yes. The book assumes that you understand the basics of Java which it sounds like you have. It will provide you with a good overview of what is available in Java 8. One thing that I do different from other Java 8 books is that I spend more time with default methods and functional interfaces. Most of everything else flows from these features. Once you have mastered them, then the other concepts fall into place more easily.