I read this book
http://www.amazon.de/Certified-Professional-Programmer-1Z0-804-1Z0-805/dp/1430247649/ref=sr_1_4?ie=UTF8&qid=1394963481&sr=8-4&keywords=ocjp which is I guess the only one containing
Java 7 topics (for some reasons the Kathy Sierra book is not available for Java 7).
There are also 2,5 mock tests (90 + 90 + 45) contained in the book. One week before the exam I bought 30 days accout from Kaplan (69 $) which is Oracle certified partner for java training. Nevertheless, the real exam was much more harder than my preparation! There were many many questions about streams (IO + NIO) and the "old style" concurrency (especially, multithreading questions leading to the data race, proper locking of the shared resources ...). There were also very tricky questions about formatting (printf, %2$s, ...).
But finally I managed the exam and achieved 81%. I would recommend to code as much as possible and try to solve the edge cases. Maybe there are some better exam questions sources than those I used. Can you recommend some of them ... maybe I will need them for Java 8 upgrade (hopefully Java 8 will come soon ;-)).
So long
golbie