1Z0-830 Java 21 Interfaces and Enums Guide

Study 1Z0-830 Java 21 Interfaces and Enums: key concepts, common traps, and exam decision cues.

This chapter is smaller, but it touches many larger questions. Functional interfaces lead into lambdas, and enum behavior often appears inside switch or API-design stems.

Work this chapter in order

Lesson	Focus
6.1 Interfaces and Enums	Learn how the exam tests interface contracts, default-method conflicts, and enum behavior as real types.

Fast routing inside this chapter

If the question is really about…	Go first to…
lambda target types or functional-interface legality	6.1 Interfaces and Enums
default-method conflict resolution	6.1 Interfaces and Enums
enum fields, methods, constructors, or constant-specific behavior	6.1 Interfaces and Enums

What strong answers usually do

treat interfaces as contracts with exact member rules
remember enums are full Java types, not just named constants
resolve default-method conflicts explicitly instead of hoping Java guesses

In this section

1Z0-830 Java 21 Interfaces, Default Methods, and Enums Guide
Study 1Z0-830 Java 21 Interfaces, Default Methods, and Enums: key concepts, common traps, and exam decision cues.

Revised on Sunday, May 10, 2026

5. Inheritance

7. Exceptions