001 /* Enumeration.java -- Interface for enumerating lists of objects
002 Copyright (C) 1998, 1999, 2001, 2004, 2005
003 Free Software Foundation, Inc.
004
005 This file is part of GNU Classpath.
006
007 GNU Classpath is free software; you can redistribute it and/or modify
008 it under the terms of the GNU General Public License as published by
009 the Free Software Foundation; either version 2, or (at your option)
010 any later version.
011
012 GNU Classpath is distributed in the hope that it will be useful, but
013 WITHOUT ANY WARRANTY; without even the implied warranty of
014 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 General Public License for more details.
016
017 You should have received a copy of the GNU General Public License
018 along with GNU Classpath; see the file COPYING. If not, write to the
019 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
020 02110-1301 USA.
021
022 Linking this library statically or dynamically with other modules is
023 making a combined work based on this library. Thus, the terms and
024 conditions of the GNU General Public License cover the whole
025 combination.
026
027 As a special exception, the copyright holders of this library give you
028 permission to link this library with independent modules to produce an
029 executable, regardless of the license terms of these independent
030 modules, and to copy and distribute the resulting executable under
031 terms of your choice, provided that you also meet, for each linked
032 independent module, the terms and conditions of the license of that
033 module. An independent module is a module which is not derived from
034 or based on this library. If you modify this library, you may extend
035 this exception to your version of the library, but you are not
036 obligated to do so. If you do not wish to do so, delete this
037 exception statement from your version. */
038
039 package 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 */
064 public 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 }