1Z0-830 Overview — Java SE 21 Developer Professional

Java SE 21 Developer Professional validates that you can read, write, and reason about modern Java code confidently.

What you should be able to do

• Use core OOP features: classes, interfaces, inheritance, polymorphism, encapsulation.
• Work with generics and understand variance (? extends / ? super) at a practical level.
• Use collections correctly and recognize mutability and ordering characteristics.
• Write stream pipelines and choose correct intermediate/terminal operations.
• Handle exceptions correctly (checked vs unchecked, try-with-resources, flow).
• Understand core concurrency building blocks (threads, executors, synchronization) at a practical level.

Efficient prep strategy

1. Use the Syllabus as your checklist.
2. Drill code-reading questions daily (most misses are “small correctness mistakes”).
3. Use the Cheatsheet for last‑mile API patterns.