The Java collections framework provides interfaces corresponding to some of the most commonly used abstract data types: List, Map, Set, etc. One abstract data type that is not included is the Multiset, which you will implement in this project.
The Double Ended Queue, or Deque, pronounced “deck”, is an abstract data type that allows elements to be appended and removed from either end of a sequence. The Java collections framework includes a [Deque] (https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/Deque.html) interface along with several implementing classes. These include the ArrayDeque, implemented using a circular dynamic array, and LinkedList, implemented using a doubly-linked list.