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.