Books focus is not to make you learn 100's of questions and asnwers, and not to teach you enormous details in 500 pages, Instead emphasis on you having notion of key concepts
Its said lot of Java Coffee was consumed by Java language creators. The cover image is tribute to Java Island in Indonesia where coffee beans called "Java Coffee" are produced. The cover image expresses island, though Java is huge island.
"A chapter won't last longer than your coffee".