Further Reading
The Java Programming language Third Edition by Ken Arnold, James Gosling and David Holmes is a good introductory text on Java programming language. As you might have noticed, one of the authors is James Gosling, the person credited with inventing Java. This book is fine for Java language but you must look for other sources for information on specific APIs. Sun's Java website, http://java.sun.com, is a good place to start such a search.
For learning more about Java security capabilities and APIs, continue reading rest of the chapters in this book. For J2SE security APIs, Java Security 2nd Edition by Scott Oaks provides a solid and comprehensive description.
Designing Enterprise Applications with the Java2 Platform, Enterprise Edition by Nicholas Kassem et al. provides a helpful overview of J2EE APIs and several architectural patterns to build enterprise applications.