001/* Enumeration.java -- Interface for enumerating lists of objects
002   Copyright (C) 1998, 1999, 2001, 2004, 2005
003   Free Software Foundation, Inc.
004
005This file is part of GNU Classpath.
006
007GNU Classpath is free software; you can redistribute it and/or modify
008it under the terms of the GNU General Public License as published by
009the Free Software Foundation; either version 2, or (at your option)
010any later version.
011
012GNU Classpath is distributed in the hope that it will be useful, but
013WITHOUT ANY WARRANTY; without even the implied warranty of
014MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
015General Public License for more details.
016
017You should have received a copy of the GNU General Public License
018along with GNU Classpath; see the file COPYING.  If not, write to the
019Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02002110-1301 USA.
021
022Linking this library statically or dynamically with other modules is
023making a combined work based on this library.  Thus, the terms and
024conditions of the GNU General Public License cover the whole
025combination.
026
027As a special exception, the copyright holders of this library give you
028permission to link this library with independent modules to produce an
029executable, regardless of the license terms of these independent
030modules, and to copy and distribute the resulting executable under
031terms of your choice, provided that you also meet, for each linked
032independent module, the terms and conditions of the license of that
033module.  An independent module is a module which is not derived from
034or based on this library.  If you modify this library, you may extend
035this exception to your version of the library, but you are not
036obligated to do so.  If you do not wish to do so, delete this
037exception statement from your version. */
038
039package java.util;
040
041/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
042 * "The Java Language Specification", ISBN 0-201-63451-1.
043 * Status:  Believed complete and correct
044 */
045
046/**
047 * Interface for lists of objects that can be returned in sequence. Successive
048 * objects are obtained by the nextElement method.
049 * <p>
050 * As of Java 1.2, the Iterator interface provides the same functionality, but
051 * with shorter method names and a new optional method to remove items from the
052 * list. If writing for 1.2, consider using Iterator instead. Enumerations over
053 * the new collections classes, for use with legacy APIs that require them, can
054 * be obtained by the enumeration method in class Collections.
055 *
056 * @author Warren Levy (warrenl@cygnus.com)
057 * @author Eric Blake (ebb9@email.byu.edu)
058 * @see Iterator
059 * @see Hashtable
060 * @see Vector
061 * @since 1.0
062 * @status updated to 1.4
063 */
064public interface Enumeration<E>
065{
066  /**
067   * Tests whether there are elements remaining in the enumeration.
068   *
069   * @return true if there is at least one more element in the enumeration,
070   *         that is, if the next call to nextElement will not throw a
071   *         NoSuchElementException.
072   */
073  boolean hasMoreElements();
074
075  /**
076   * Obtain the next element in the enumeration.
077   *
078   * @return the next element in the enumeration
079   * @throws NoSuchElementException if there are no more elements
080   */
081  E nextElement();
082}