Joda-time

Several alternative Date replacement packages emerged, including the simple and sensible Date4J and the more comprehensive Joda-Time package.

Joda time is a complete alternative to the JDK date and time classes and seeks to replace them.

Joda-Time is a powerful open source library well known and used in the market that works with time, dates, and chronology:

Later the decision was made to integrate Joda-Time or something similar to it into Java's core libraries

The design of these classes was inspired by the Joda-Time library, which is a popular open-source date and time library for Java.

For instance, when integrating a date-time library like Joda-Time, one might wrap the mutable Java objects in immutable records, thereby providing a clear boundary between side-effecting Java calls and pure Clojure functions.