Introduction to Programming

java.util

This is another very commonly used package. Most of its content is dedicated to support collections:

• The Collection interface – the base interface of many collection interfaces. It contains all the basic methods necessary to manage collection elements: size(), add(), remove(), contains(), iterator(), stream(), and others. Notice that the Collection interface extends the Iterable interface and inherits the iterator() method from it. This means that any implementation of the Collection interface can be used in iteration statements.
• Interfaces that extend the Collection interface: List, Set, Queue, Deque, and many others.
• Many classes that implement the forementioned interfaces: ArrayList, LinkedList, HashSet, AbstractQueue, ArrayDeque ...