At the "Writing the Next Great Java Book" BOF at JavaOne, there were unfortunately many more questions than we had time to answer. Fortunately, Greg Doench saved the questions (presciently, they were submitted on paper), so I'll answer a few here.
Q: About how much time did you put into your book (effort, not duration)?
A: In my case, the answers for effort and duration are the same, as I had the luxury of writing the book mostly-full-time -- I made the book my foreground activity, though I still did some consulting and training while I was working on it. I spent approximately 16 months on the book -- longer than planned (but in hindsight is no surprise.)
Q: Was the financial compensation worthwhile?
A: Unless your name is Stephen King or JK Rowling, writing books is not something you do for the financial compensation. This is more true for technical books, because (a) the audience for books like Java Concurrency in Practice is not quite as large as the audience for Harry Potter, and (b) if you have the skills to write a good technical book you probably have the skills to get a well-paying technical job. Without going into the details, I'll say that the compensation is about what I expected -- but I went into it with very realistic expectations. The compensation comes in other forms.
Q: How much support and assistance was provided by the publisher?
A: I think this is a matter of how much support and assistance you ask of the publisher -- and how much the publisher thinks you need. In our case, we did everything ourselves, including typesetting and managing the review, copy editing, and index creation. These are things the publisher often does for authors (and might even have preferred to do), but we chose to do it ourselves, and the publisher agreed. Of course, this was more work, but it was work we gladly did. The A-W team was always responsive when we did ask for things. So I think the answer is "as much as you appear to need."
Q: How does the short half-life of technical topics affect the effort?
A: I deliberately chose a topic with a longer half-life. This gave me the latitude to let the book tell me when it was done, rather than the schedule. For material with a shorter shelf life, I might be inclined to choose a shorter format, so that the book is less out-of-date by the time it is published.
Q: What would you say about books that authors release chapters to the public as they write?
A: I think this presupposes a style of writing where the author sits down and writes the book linearly. I am sure some authors do this, and some topics are more amenable to this approach than others. But one of the most important freedoms in writing is the freedom to refactor continuously; very often you don't figure out the right way to present the material until you've presented it the wrong way (just as with code.) There's nothing wrong with putting the work out there early -- this is a great source of free review -- but you have to be careful that doing so doesn't cause you to settle into the belief that the structure of the book has been decided. (The same risk is true of trying to adhere to a schedule that assigns due dates to specific chapters.)
Q: How do you avoid example source code exploding without using unrealistic examples?
A: This is really hard! But its really important. In JCiP, we set a rule for ourselves of "no code example more than a page", with the target of making most of them a half page or less. This is not easy, especially in Java! (There was only one we had to break into two separate one-page listings.) We wanted the examples to each illustrate a single point, so that the reader could look at the example and easily see what it was trying to show. There are some obvious tricks; eliminating boilerplate code like constructors, getters, and setters helps a little bit. What worked for us was to pick realistic examples that the audience would immediately understand the utility of (such as a file crawler), but abstract away the irrelevant concrete details by not showing the bodies of methods that are not needed to make the point that the example is supposed to illustrate. For example, we have a set of examples in Chapter 8 where we illustrate searching for solutions to a class of puzzles such as the "sliding block puzzles." But rather than focus on a specific puzzle -- which would take lots of space and not offer all that much insight, we abstract the nature of the puzzle by defining an interface that specifies the initial position (in terms of an abstract Position class), valid moves (in terms of an abstract Move class), and the goal position. Then we can illustrates various search techniques in terms of the abstract puzzle without getting bogged down in the details.
Q: What would you say is the role of technical books in the age where the Internet is the fastest way to publish texts and technology changes so fast that one year after publishing texts become irrelevant?
A: Some technical books are simply a form of documentation; any book that has a version number in the title is likely to fall into this category. These books have a very short shelf life. Other books, those that tend to focus on concepts rather that specific technical details, tend to have a longer shelf life. In any case, the publishing industry needs to become more agile in its approach to managing the authoring and production process, and explore more seriously alternate publication vectors such as electronic publishing.