I started working on Java in 1999 and I got my first Java certification in 2000, that's 16 years ago!
I got all 5 AWS Certifications this year!
Then I look back, Java has changed so much. I planned to get certified in Java 8.
I am on vacation now so I started preparing for it. I started reading Jeanne Boyarsky and Scott Selikoff's book on 12/23/2016 and passed OCA on 12/27/2016.
Then I started reading OCP and passed the OCP today!
I booked the exam yesterday and the normal site was fully booked so I had to drive to a new exam center but it was OK.
Besides the experience I had in Java 8, and Java Docs API, these books are the only materials I read. I read, practiced and tried to understand why I made mistakes.
I passed OCA at 91% and OCP at 86% on a preparation of 4 days each.