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

/*
 *  Example of element() and peek() methods.
 */
public class DequeExample
{

    public static void main(String[] args)
    {
        Deque<Integer> deque = new LinkedList<Integer>();
        deque.add(200);
        deque.add(300);
        deque.add(400);
        deque.add(500);

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

        /*
         * Retrieves, but does not remove, the head of the queue represented by
         * this deque (in other words, the first element of this deque). This
         * method differs from peek only in that it throws an exception if this
         * deque is empty.
         */
        Integer element = deque.element();

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

        /*
         * Retrieves, but does not remove, the head of the queue represented by
         * this deque (in other words, the first element of this deque), or
         * returns null if this deque is empty.
         */

        element = deque.peek();
        System.out.println("element : " + element);
        System.out.println("deque : " + deque + "\n");

    }

}