The most important thing to know is that from Java 7 onward, Oracle had split the Java Professional certification into two exams - Java Associate level and Professional level. To become a Java 8 certified professional, you need to first pass OCA before taking OCP, which means you need to pass two exams to become an Oracle certified Java professional.
To acquire the latest Java 8 Professional Certification (OCP8), you need to first pass the Java 8 Associate Certification (OCA 8). In other words, you have to take two exams - 1Z0-808 (Java SE 8 Programmer I) and 1Z0-809 (Java SE 8 Programmer II).
This has changed for the good and now you can become an Oracle certified Java professional by passing just one exam, Java SE 11 Developer, OCP 11, or 1Z0-819. This is the main reason I am asking Java developers to go for Java SE 11, combined with its also the latest Java certification available in the market.
Though, if you hold any older Java certification like Java SE 5, 6, or 7 then you can also take an upgrade exam for Java SE 8 and Java SE 11 and can eventually become a certified Java developer by passing one exam.
Another reason to go for Java SE 11 certification is that it's the most up-to-date certification. I highly recommend this exam to new developers who are trying to get Java certification, because Java 11 certification covers several new features in the language and will provide a competitive advantage to you on Interviews. It's also better to learn the future way of using Java sooner than later.
If you already made your mind and preparing for Java SE 11 certification then I highly recommend you to check out my article The Ultimate Guide to Pass Java 11 Certification (1Z0-819) Exam in 2021