In July 2024, Oracle officially released the new Java 21 Certification Exam (1Z0-830). Unlike some developers who passed it on their first attempt, it took me two tries to succeed. I’d like to share my experience—both the challenges and the lessons learned—to help others who are preparing for this certification.

First attempt: underestimated the time

I dedicated about a month to studying for the first attempt. For my studies I used the official certification book:

I also used a simulator provided by Enthuware:

However, I was caught off guard by the exam's complexity. Many questions were significantly long, often requiring extensive scrolling and deep concentration. This consumed a lot of time, and unfortunately, I scored only 54%, which was not enough to pass.

Preparing for the Second Attempt

Oracle requires a 5-day waiting period before you can retake the exam. Since the exam isn't available on weekends, I scheduled my retake for the following Friday at 5:00 AM. Rescheduling was simple—there’s a link in the confirmation email, and the interface is the same as booking the initial exam.

Between attempts, I spent two focused weeks reviewing key topics, working through mock exams, and refining my strategy. This time, I passed with 82%—a significant improvement, though I still felt the time pressure. I had some minutes left at the end to review some answers.

Exam Day Tips

Check in early. I strongly recommend checking in at least 20 minutes before your exam starts to avoid any technical or verification delays.

The format of the exam was similar to my first attempt, with several lengthy questions—some requiring significant scrolling due to the amount of code. These take up a lot of time, so pacing is essential.

This time, I applied two new techniques:

Using the mouse cursor as a reading guide helped me stay focused while scanning code.
Thinking out loud in my head, as if explaining my reasoning to someone else, helped reduce careless mistakes.

Interestingly, a few questions were repeated from my previous attempt. While I recognized them and was quicker to respond, I made a conscious effort to slow down and double-check everything. My previous failure wasn’t due to lack of knowledge but from rushing through questions and making avoidable errors.

Exam Content

On my second attempt, I saw a notable number of questions on:

Pattern Matching
Virtual Threads
Sequenced Collections

These topics appear to be a key focus area for the Java 21 exam, so I’d recommend spending extra time mastering them.

After the Exam

Once I passed, I immediately removed the LockDown Browser software from my machine— it has deep system permissions, and I prefer not to keep it installed longer than necessary.

Next, I visited the CertView page to access my results and badge.

To access your detailed exam report:

Navigate to “Exam Results” on the left panel
Click “Exam History”
Select “Results” for your latest exam to download a PDF. This will show which objectives you answered incorrectly.

To access your credentials:

Expand “Credential Management” in the sidebar
From here, you can download your certificate, badge, or share your credentials directly to LinkedIn or via email.

Final Thoughts

The Java 21 certification exam is no easy feat. It’s comprehensive, time-sensitive, and emphasizes newer features in the language. My advice: take your time, focus on understanding rather than memorization, and simulate the testing experience as much as possible before your actual exam.

If you're planning to take 1Z0-830, I hope this insight gives you a better idea of what to expect—and how to prepare effectively.

Good luck!

My Experience with the Java 21 Certification Exam (1Z0-830)