Books for Java CertificationMost Popular
SCJP for for Java 6 Exam 310-065 by Kathy Sierra and Bert Bates is the most popular book on Java Certification. If you are new to Java, this book is the best buy. It is written by the founder of Javaranch and covers the latest version of the exam. There is a kindle edition of the book also available.
A Programmer's Guide to Java Java Certification by Khalid Azim Mughal, Rolf Rasmussen is the best book on Java Certification. Its standard is slightly above the actual exam, hence it can give you more confidence. It is also a good reference book after you have cleared your certification.
Another good one
SCJP: Sun Certified Programmer for Java Platform Study Guide: SE6 (Exam CX-310-065) by Richard Raposa is another nice book on SCJP 6. It covers the topic in the exam at a fast pace, and is a good second book for certification aspirants.