First I would like to differentiate the topic of Java into three phases: First learn how to program, second learn how to program in an object oriented way and only then learn whatever framework you like. Unfortunately I see that most junior developers have serious deficiencies in the first two areas, whereas frameworks are well known. I met developers who knew the Spring Framework pretty well, but had never heard of Test Driven Development and had no idea what the Java keywords
transientare supposed to do.
For the first phase I refer to the most influential book every programmer should read. There you see that the most important book (as seen by the StackOverflow community) is Code Complete. The second important book is The Pragmatic Programmer. I think it's even more important than Code Complete. This book is the base of all development work. I'm sure you will like it. It has around 350 pages and for an experienced developer only a few chapters will be new. But on the other hand, I still meet people that do not use version control or build automation. That's one reason that everybody has to read it. Now go, read it! Even if you are an expert, just go and read it! ;-)
The SCJP Study Guide is a good start for Java. There is no way around knowing operator precedence and other low level details of the language. Another book on Java basics like TIJ (Thinking in Java) is necessary to deepen the knowledge after the SCJP guide, which is just focusing on the very basics. Then I highly recommend Java Generics and Collections to comprehend Java Generics. Of course no list of Java books is complete without Effective Java which is also very important. To round up the basic Java knowledge I recommend the Java Language Specification. It's a specification but it's not that bad to read.
After the basics I would definitely add Kent's Beck Test Driven Development by Example, which is a short and excellent introduction to JUnit and TDD. And of course you must read Design Patterns, Refactoring, Clean Code - argh, more and more books get piling up. Think about it, you will not become a professional (Java) developer by reading three books, you probably need more than that, maybe 30 ;-) So if you feel like more books, just check out my Goodreads reading list. All books I've read are rated and tagged accordingly. I encourage to have a look. I'm looking forward to see your recommendations.