This one get's used daily. I'm a little surprised by the other reviews. I have found over the last year this to be an authorative source for the Java Language Specification. I go to other books when I want to know about the various Java packages but this is the one I got to when I want to know about the Java langauge semantics and syntax.
Don't buy it This is the worst book on programming I've ever bought. Even though the author does tell the reader that this book isn't intended as a "teach yourself"-book one expects a book on programming to be somehow divided into well defined areas, each showing a part of the whole idea. This book switches from reference style to programming-by-example style all mixed up with a couple of bad flow charts. I regret buying it and advise others from doing it.Shy on the details There are several places in the language description (for example, the rules on static method overriding and inner classes) where this book is either vague, misleading, or occasionally flat-out wrong. "Java Language Reference" might provide a nice introduction to the language's syntax, but it does not make a good Java language reference.