Java ArrayList.add() is a method in the Java ArrayList class that appends the specified element to the end of the list. It dynamically increases the size of the list as elements are added. Introduced in Java 1995 with Java 1.2, add() is a fundamental method for list manipulation in Java and is used to dynamically build or extend lists with new elements.

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