import java.util.Deque;
import java.util.Iterator;
import java.util.LinkedList;

public class DequeExample {

    public static void main(String[] args) {
        Deque deque = new LinkedList<>();

        // We can add elements to the queue in various ways
        deque.add("Element 1 (Tail)"); // add to tail
        deque.addFirst("Element 2 (Head)");
        deque.addLast("Element 3 (Tail)");
        deque.push("Element 4 (Head)"); //add to head
        deque.offer("Element 5 (Tail)");
        deque.offerFirst("Element 6 (Head)");
        deque.offerLast("Element 7 (Tail)");

        System.out.println(deque + "\n");

        // Iterate through the queue elements.
        System.out.println("Standard Iterator");
        Iterator iterator = deque.iterator();
        while (iterator.hasNext()) {
            System.out.println("\t" + iterator.next());
        }

        // Reverse order iterator
        Iterator reverse = deque.descendingIterator();
        System.out.println("Reverse Iterator");
        while (reverse.hasNext()) {
            System.out.println("\t" + reverse.next());
        }

        // Peek returns the head, without deleting it from the deque
        System.out.println("Peek " + deque.peek());
        System.out.println("After peek: " + deque);

        // Pop returns the head, and removes it from the deque
        System.out.println("Pop " + deque.pop());
        System.out.println("After pop: " + deque);

        // We can check if a specific element exists in the deque
        System.out.println("Contains element 3: " + deque.contains("Element 3 (Tail)"));

        // We can remove the first / last element.
        deque.removeFirst();
        deque.removeLast();
        System.out.println("Deque after removing first and last: " + deque);
    }
}

Output:

[Element 6 (Head), Element 4 (Head), Element 2 (Head), Element 1 (Tail), Element 3 (Tail), Element 5 (Tail), Element 7 (Tail)]

Standard Iterator
Element 6 (Head)
Element 4 (Head)
Element 2 (Head)
Element 1 (Tail)
Element 3 (Tail)
Element 5 (Tail)
Element 7 (Tail)
Reverse Iterator
Element 7 (Tail)
Element 5 (Tail)
Element 3 (Tail)
Element 1 (Tail)
Element 2 (Head)
Element 4 (Head)
Element 6 (Head)
Peek Element 6 (Head)
After peek: [Element 6 (Head), Element 4 (Head), Element 2 (Head), Element 1 (Tail), Element 3 (Tail), Element 5 (Tail), Element 7 (Tail)]
Pop Element 6 (Head)
After pop: [Element 4 (Head), Element 2 (Head), Element 1 (Tail), Element 3 (Tail), Element 5 (Tail), Element 7 (Tail)]
Contains element 3: true