JodaTime

Joda-Time is an open-source date and time library for Java. It provides a comprehensive, consistent API for handling dates, times, time zones, durations, and chronology, addressing shortcomings of the built-in java.util.Date and Calendar classes.

Developed by Stephen Colebourne and others, Joda-Time was released in 2007 and became widely adopted as the de facto standard time library in Java before the introduction of the java.time (JSR-310) API in Java 8. Its emphasis on immutability and a fluent API aimed to reduce bugs and threading issues.

Its core types include DateTime (an immutable instant with a time zone), LocalDate, LocalTime, LocalDateTime, Instant, Interval, Duration, and Period. Time zones are handled via DateTimeZone, and multiple calendar systems are supported via Chronology, though ISO chronology is the default. All classes are immutable and thread-safe.

It offers precise arithmetic, parsing and formatting using DateTimeFormatter equivalents, and robust interval and range operations with Interval and Period. While it remains usable in existing projects, maintainers recommend migrating to java.time for new development when possible, as Joda-Time is in maintenance mode.

Joda-Time influenced the design of java.time; the modern Java time API integrates concepts such as clocks, instants, local and zoned date/time, and durations that mirror Joda-Time's approach.