JSR310

JSR 310, Java Specification Request 310, defined a new date and time API for the Java platform. It aimed to replace the older java.util.Date and Calendar with a modern, immutable, and thread-safe API that cleanly separates date, time, and time-zone concerns. Led by Stephen Colebourne and other contributors, the specification culminated in Java SE 8 (2014).

The API introduced the java.time package, with core classes such as LocalDate, LocalTime, LocalDateTime, ZonedDateTime, OffsetDateTime, and Instant, plus Duration, Period, Clock, and ZoneId. It relies on ISO-8601 formats by default and provides a fluent API for construction, modification, and comparison, along with DateTimeFormatter for parsing and formatting.

Key design traits include immutability and thread-safety, explicit handling of time zones and offsets, and a clear separation of concerns among date, time, duration, and calendar concepts. The API defines Temporal, TemporalAccessor, ChronoUnit, ChronoField, and TemporalAdjuster to support extensibility and testing, including a Clock abstraction for controllable time sources.

Adoption and interoperability: JSR 310 became the standard date-time API in Java 8, widely adopted in Java applications. It interoperates with legacy code via conversions to and from java.util.Date and Calendar through the Instant and related types.