package jds;

import java.util.Enumeration;
import java.io.Serializable;

/**
 * Base class for jds Container hierarcy; 
 * for use with book
 * <a href="http://www.cs.orst.edu/~budd/books/jds/">Classic Data Structures 
 * in Java</a>
 * by <a href="http://www.cs.orst.edu/~budd">Timothy A Budd</a>, 
 * published by <a href="http://www.awl.com">Addison-Wesley</a>, 2001.
 *
 * @author Timothy A. Budd
 * @version 1.1 September 1999
 * @see java.util.Enumeration
 * @see java.io.Serializable
 */

public interface Collection extends Serializable {

	/**
	 * Determines whether the collection is empty
	 *
	 * @return true if the collection is empty
	 */
	public boolean isEmpty ();

	/**
	 * Determines number of elements in collection
	 *
	 * @return number of elements in collection as integer
	 */
	public int size ();

	/**
	 * Yields enumerator for collection
	 *
	 * @return an <code>Enumeration</code> that will yield the elements of the collection
	 * @see java.util.Enumeration
	 */
	public Enumeration elements ();
}