ThreeTenABP

ThreeTenABP, short for the ThreeTen Android Backport, is an open-source library that provides a backport of the Java SE 8 date and time API (JSR-310) for Android. It enables developers to use the modern, immutable, and thread-safe java.time-inspired API on devices where the standard library does not include it. The API surface mirrors java.time, offering classes such as LocalDate, LocalTime, LocalDateTime, ZonedDateTime, Instant, Duration, and Period, under the org.threeten.bp and related packages. Time-zone support is included through ZoneId, ZoneOffset, and ZoneRules, and formatting utilities are available via DateTimeFormatter.

ThreeTenABP is the Android-specific port of the broader ThreeTen project and is maintained by the community. It relies on the IANA time zone database to provide accurate zone rules and transitions. The library is designed to be source-compatible with java.time where possible, making it familiar to developers already using the Java 8 API.

Usage and installation typically involve adding a dependency from Maven Central and initializing the library at application startup. A common pattern is to include a Gradle dependency on com.jakewharton.threetenabp:threetenabp and to call AndroidThreeTen.init(context) from the Application class before using the API. After initialization, Android code can reference org.threeten.bp types just as with java.time, for example LocalDate.now() or ZonedDateTime.now(ZoneId.systemDefault()).

Limitations include that ThreeTenABP, while feature-rich, may not implement every niche aspect of java.time and some behavior can differ across Android versions. It remains a practical backport for Android development where java.time is unavailable.