1Z0-830 Java 21 Date/Time API Guide

Study 1Z0-830 Java 21 Date/Time API: key concepts, common traps, and exam decision cues.

This chapter is lighter than streams or OOP, but it is still a clean source of exam points if you keep immutability, zones, and date-vs-time duration logic straight.

Work this chapter in order

Lesson	Focus
2.1 Core Time	Learn how to choose the right date/time type and avoid zone, formatting, and DST mistakes.

Fast routing inside this chapter

If the question is really about…	Go first to…
choosing between `LocalDate`, `Instant`, and `ZonedDateTime`	2.1 Core Time
`Period` vs `Duration`, formatting, or parsing	2.1 Core Time
daylight saving time or zone conversion	2.1 Core Time

What strong answers usually do

choose the type that actually models the requirement instead of the most familiar class
remember the API is immutable and returns new values
treat time-zone logic as an explicit part of the problem, not an afterthought

In this section

1Z0-830 Java 21 Core Types, Zones, Manipulation and DST Guide
Study 1Z0-830 Java 21 Core Types, Zones, Manipulation and DST: key concepts, common traps, and exam decision cues.

Revised on Sunday, May 10, 2026

1. Types

3. Flow