The two most popular implementation of Deque interface in Java

are:

1. ArrayDeque: It is a resizable array implementation of

Deque. The capacity of ArrayDeque can increase based

on the need of the program. It is not thread safe

implementation. Also the iterator on ArrayDeque is failfast.

2. LinkedList: This is another popular implementation of

Deque interface in Java. It is also not synchronized, so it

is not thread-safe. It mainly provides functionality of a

doubly linked list.

https://www.softwaretestinghelp.com/deque-in-java/