java.time · java.base · since Java 1.8

Instant

declaration

public final class Instant
        implements Temporal, TemporalAdjuster, Comparable<Instant>, Serializable

A point on the UTC timeline (epoch seconds + nanos) — THE type for event timestamps, logs, and persistence. Zone-free by definition.

Key methods

`static Instant now() / now(Clock clock)`	Current moment (inject Clock for testability).
`static Instant ofEpochMilli(long) / long toEpochMilli()`	Legacy epoch-millis bridge.
`Instant plus(Duration) / isBefore(Instant)`	Machine-time arithmetic and comparison.
`ZonedDateTime atZone(ZoneId)`	Up to human calendar terms for display.