/**
 * A Queue is a repository for Objects maintained in first-in first-out order.
 * Objects are inserted using enqueue and removed using dequeue. 
 * Objects are removed in the same order in which they are inserted.
 */

interface Queue
{
/**
 * Insert an Object in the queue.
 *
 * @param item the Object to be inserted
 */

void enqueue(Object item);


/**
 * Remove an Object from the queue.
 *
 * @return the Object removed
 * @exception EmptyQueueException if the Queue is empty
 */

Object dequeue() throws EmptyQueueException;


/**
 * Indicate whether or not the Queue is empty
 *
 * @return boolean indicating whether or not the Queue is empty
 */

boolean isEmpty();

}