The SCJP or Sun Certified Java Programmer accreditation status is granted to advanced or highly skilled Java Programmers. They get certified by taking an exam for Java certification. Most of the time, employers prefer an employee who is certified over employees who are not. Even if a Java programmer has abilities at the same level as those who are certified, he might get overlooked by employers who still favor those programmers who are certified.
If you are considering a serious career in Java programming, you may think of getting yourself an SCJP accreditation. There are ways to prepare for examination if you are one of those people who aim for SCJP. There are downloadable programs that simulate the real SCJP exams these are called mock exams and are available on the Internet. Some are offered for free (as trial versions) and some are sold for a couple of hundreds of dollars but may have guarantees to pay you back (with interest sometimes) if you fail the accreditation exam.
There are many SCJP books available yet finding the right one seems to be yet another challenge for an SCJP exam taker. The most recommended books for SJCP would be the Sun Certified Programmer & Developer for Java 2 Study Guide; and A Programmers Guide to Java.
The latest release for Java certification book is the Sun Certified Programmer & Developer for Java 2 Study Guide written by Kathy Sierra and Bert Bates (a creation of the Javaranch founder.) The book offers information for people who are new to Java and also covers the latest version of SCJP exam.
The second book, considered by some as the best book for Java certification, is A Programmers Guide to Java, written by Khalid Azim Mughal and Rolf Rasmussen. The book offers slightly above average standards for taking the real exam while giving the exam taker the confidence he needs. The exam taker may still use this book even after gaining certification.