Java Calendar is an abstract class used for converting between specific Java Dates and manipulating date and time information in Java. It provides methods like Java get(), Java set(), and Java add() to retrieve, modify, and calculate date and time values. Introduced in Java 1995 with Java 1.0, Calendar has been largely replaced by the Java LocalDate and Java LocalDateTime classes introduced in Java 8 for more modern and thread-safe date-time handling.

https://docs.oracle.com/javase/8/docs/api/java/util/Calendar.html