Note on the cover design
The cover of Thinking in Java is inspired by the American Arts & Crafts Movement that began near the turn of the century and reached its zenith between 1900 and 1920. It began in England as a reaction to both the machine production of the Industrial Revolution and the highly ornamental style of the Victorian era. Arts & Crafts emphasized spare design, the forms of nature as seen in the art nouveau movement, hand-crafting, and the importance of the individual craftsperson, and yet it did not eschew the use of modern tools. There are many echoes with the situation we have today: the turn of the century, the evolution from the raw beginnings of the computer revolution to something more refined and meaningful to individual persons, and the emphasis on software craftsmanship rather than just manufacturing code.
I see Java in this same way: as an attempt to elevate the programmer away from an operating-system mechanic and toward being a software craftsman.
Both the author and the book/cover designer (who have been friends since childhood) find inspiration in this movement, and both own furniture, lamps, and other pieces that are either original or inspired by this period.
The other theme in this cover suggests a collection box that a naturalist might use to display the insect specimens that he or she has preserved. These insects are objects that are placed within the box objects. The box objects are themselves placed within the cover object, which illustrates the fundamental concept of aggregation in object-oriented programming. Of course, a programmer cannot help but make the association with bugs, and here the bugs have been captured and presumably killed in a specimen jar, and finally confined within a small display box, as if to imply Javas ability to find, display, and subdue bugs (which is truly one of its most powerful attributes).