I passed the 1Z0-808 Java SE 8 Programmer I with 80%.
The resources I used were:
1. Head First Java 2nd Edition – Covers Java 5.0 by Kathy Sierra & Bert Bates
2. OCA: Oracle Certified Associate Java SE 8 Programmer I Study Guide by Jeanne Boyarsky and Scott Selikoff
3. This Forum of course
When I reading the OCA: Oracle Certified Associate Java SE 8 Programmer I Study Guide, authors suggested that it would be good if you has some basic or if you have never written a Java program before (im from C# background), they recommend pick up any version of Java. Head First Java, 2nd Edition is one of the authors recommended. I find it very useful and I can read it and understood very fast.
My experience, do more practice but don’t use those Intellij or similar products. Im using Notepad++, every time I had compiled error, I did learn something from there, this help me remember the syntax and rules better, because debuging the code you can find out more information.