/**
   An interface for the ADT priority queue.
   @author Frank M. Carrano
   @author Timothy M. Henry
   @version 4.0
*/
public interface PriorityQueueInterface<T extends Comparable<? super T>>
{
   /** Adds a new entry to this priority queue.
       @param newEntry  An object to be added. */
   public void add(T newEntry);

   /** Removes and returns the entry having the highest priority.
       @return  Either the object having the highest priority or, if the
                priority queue is empty before the operation, null. */
   public T remove();

   /** Retrieves the entry having the highest priority.
       @return  Either the object having the highest priority or, if the
                priority queue is empty, null. */
   public T peek();

   /** Detects whether this priority queue is empty.
       @return  True if the priority queue is empty, or false otherwise. */
   public boolean isEmpty();

   /** Gets the size of this priority queue.
       @return  The number of entries currently in the priority queue. */
   public int getSize();

   /** Removes all entries from this priority queue. */
   public void clear();
} // end PriorityQueueInterface