Oracle has several paths to certification. Those who hold older versions of the certification have choices of what to take. This post summarizes your options along with my opinion on which path you should choose and why. Also see What Does it Mean to be Java SE 11 Developer Certified.
Scroll down to the section that matches you:
- No Java Certification or SCJP 5 or earlier
- OCP 6, OCP 7 or OCP 8
- OCA 7 or OCA 8
- OCA 6
- Passed the OCP 7 or 8 level exam, but not the OCA 7/8 level exam.
You currently hold: No Java Certification or SCJP 5 or earlier
My recommendation: No choices here
You currently hold: OCP 6, OCP 7 or OCP 8
My recommendation: I recommend the upgrade exam. There’s a good number of topics on the part 2 exam that aren’t on the upgrade exam. So your overall effort is lower for the upgrade exam.
In the past, the upgrade exam was harder than the part 2 exam because “all the easy questions that haven’t changed from past versions of Java” don’t appear on the upgrade. However, they don’t appear on the part 2 exam either. Now they appear on the part 1 exam. The three exams are more equal in difficulty now.
You do have to study modules more for the upgrade exam because the modules topics from both part 1 and part 2 appear on it. But getting to skip a number of other objectives makes this worth it if you seek to minimize your studying.
By contrast, you will miss some topics with the upgrade route. If you want to learn as much as possible, taking the part 1/part 2 route will advance that goal.
You currently hold: OCA 7 or OCA 8
My recommendation: By the same reasoning as the previous entry, taking just part 2 is the easiest route. However, you will miss some topics. Some you might want to take both exams to learn more and build your foundational knowledge.
You currently hold: OCA 6
My recommendation: The least expensive route is definitely to just take part 2. However, the OCA 6 was nothing like the OCA 7/8. It’s a really big jump to take just part 2 so I recommend taking both.
You currently: Passed the OCP 7 or 8 level exam, but not the OCA 7/8 level exam.
My recommendation:I recommend taking part 1 and the upgrade exam. Most of the topics that are “left out” of the upgrade exam were on the OCP 7 and OCP 8 so you’ve already got those covered.