I had originally intended to buy the official Sun Java Series books, but I found that they were expensive and overly formal. To get all the current library specs requires three volumes at about $60 a piece. Plus the language spec which is written in very formal language, thus not very useful as a quick reference, and is available for free as a .pdf file should you require such formality to write a parser, for instance.

The In a Nutshell collection is perfect for my needs. It is just the sort of comprehensive resource that I was looking for, both as a working reference and as a learning tool. As a learning tool it is almost self-contained. You can look at the 'Java Examples' (The Java Cookbook by Ian Darwin is also recommended - the examples are more up to date, and the scope is broader) and find some code that approximates what you are trying to do. Then you can look at the various API calls and object heirarchies and go to the other volumes to find a description of each class and interface (Another recommendation is the set of posters that you can get bundled with "Effective Java" - also an excellent book. The posters give a visual reference of the package/class hierarchies making it very easy to understand the relationships between the various classes, sub-classes, and interface specs. A word of caution: the posters are unusually tall. I had to turn them sideways to fit them on the walls of my cube.

The reference material, typical of O'Reilly's 'Nutshell' books, is just right. Each interface is fully speced with just the right amount of verbage. You aren't left scratching your head (well, not any more that necessary) but at the same time you don't have to search endless paragraphs just to understand the syntax of one API call. It's the perfect substitute for online docs, which are never this well organized, and gives me the opportunity to pull my aching eyes away from the CRT for a moment without losing productivity.

All told, it is a very good collection that seems ideal for what I - and a lot of other professional programmers I would imagine - am doing. I can't see how any Java programmer's book collection would not be enhanced by these books.