/**
 * An interface for the Priority Queue ADT.  Note that relative priority of
 * elements is determined with the T.compareTo() method.
 * @param <T> the type of data the queue stores.
 * @author Jadrian Miles
 */
public interface PriorityQueue<T extends Comparable<? super T>> {
    
    /** Adds the given item to the queue. */
    public void add(T item);
    
    /** Removes the maximum item from the queue, and returns it.
     * @return null if the queue is empty.
     */
    public T remove();
    
    /** Returns the maximum item in the queue, without removing it.
     * @return null if the queue is empty.
     */
    public T peek();
    
    /** Returns true if the queue is empty. */
    public boolean isEmpty();
    
    /** Removes all items from the queue. */
    public void clear();
}