PriorityQueueInterface.java

/** An interface for the ADT priority queue. */
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 emtpy, 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