In Java, an ArrayDeque is a double-ended queue implementation that provides constant-time performance for adding or removing elements from either end of the deque. It is similar to a queue, but with the added ability to insert and remove elements from both ends of the deque.

To use an ArrayDeque, you first need to import it from the java.util package:

import java.util.ArrayDeque;

You can then create a new ArrayDeque instance and add elements to it. Here's an example:

ArrayDeque<String> deque = new ArrayDeque<>();
deque.add("apple");
deque.add("banana");
deque.add("cherry");

In this example, we create an ArrayDeque that stores String objects, and add three elements to it using the add method.

You can also remove elements from the deque using methods like remove, poll, and pop. For example:

String first = deque.remove();  // Removes "apple" from the deque and assigns it to `first`
String last = deque.removeLast();  // Removes "cherry" from the deque and assigns it to `last`

In this example, we remove the first and last elements of the deque using the remove and removeLast methods, respectively.

Overall, ArrayDeque is a useful data structure in Java for implementing algorithms that require fast insertion and removal from both ends of a collection.