Module 12 · Design & Idioms

Beyond the 1Z0-830 exam

The exam checks that you know the language; this module is about using it well. Immutability, the object contracts, common patterns, and a working mental model of the JVM are what separate code that compiles from code that's correct, maintainable, and reviewable — including when you're critiquing AI-generated code.

Writing Java that's correct, maintainable, and reviewable: design immutable value types, honour the equals/hashCode/Comparable contracts, reach for the right idiom, and keep a realistic picture of what the JVM is doing underneath.

Lessons

#	Lesson	What it covers
01	Immutability & Defensive Copying	Designing immutable types, copy in/out, records as value types.
02	Object Contracts & Common Patterns	equals/hashCode/Comparable in depth; builder/factory/strategy.
03	JVM Awareness	Heap vs stack, GC basics, class loading, performance intuition.

Track your progress

Your progress0 / 3 (0%)

• L01 — Immutability & Defensive Copying
• L02 — Object Contracts & Common Patterns
• L03 — JVM Awareness

Module Mini-Exam

A mixed quiz over this module. Since this is beyond-exam material, treat it as a self-check rather than exam simulation.

Mini-Exam

• 7 questions
• 12 minutes
• 7 total points
• Pass: 5 pts (68%)