With availability of Java Tutorial at the source, people around the world answering your questions, assuring your understanding, some free books, some free tutorials, free excerpts, many mock tests,.......... Is it possible to clear these certifications without purchasing a book? Does it serve the purpose of certification by just reading A book and getting certified?!
We believe that every being is divine, is God. Every soul is a sun covered over with clouds of ignorance; the difference between soul and soul is owing to the difference in density of these layers of clouds. - Swami Vivekananda
Books are only one media for transferring information from one head to another head. Books can help to manage the vast amount of very distributed information about Java. They can act as a filter to discard irrelevant information or they can enrich the information. So a good book, although not essential, is a great help to a examination candidate. Take a look in your local library or book shop there are some fine books available. Choose one with the style you like - academic style or more one of those based on cognitive psychology.
But if you want to pass an exam, any exam, without reading a book, there are, as you quite rightly remarked, excellent alternative resources to be found on the internet and elsewhere.
The certification forums are mainly populated by those who are studying to pass an examination rather than who have already passed one. Peruse our Sun Certification Results for candidates who have passed their exam but have mentioned that they used no books.
What it comes down to is that there is a wide range of resources to learn from - whether for a certification or some other goal. Some people like to learn from books, others prefer other resources. For some, the costs in terms of money is an important criterion, for others other reasons will prevail.
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
Imagine that someone who's going to save the planet needs to learn Java in pursuit of this goal. If the appropriate book saves her a hundred hours in her learning, then I'd say that's a great use of resources.
In other words, good resources can save a lot of time. If a candidate has a lot of time then perhaps piecing together the required resouces with which to study is a good call. On the other hand, for a lot of people, their time has value, and if investing in the proper, focused resources can save hours of time, the investment is a good one.
Spot false dilemmas now, ask me how!
(If you're not on the edge, you're taking up too much room.)