1 /*

     2  * Copyright 1994-2005 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package java.util;

    27 

    28 /**

    29  * An object that implements the Enumeration interface generates a

    30  * series of elements, one at a time. Successive calls to the

    31  * <code>nextElement</code> method return successive elements of the

    32  * series.

    33  * <p>

    34  * For example, to print all elements of a <tt>Vector&lt;E&gt;</tt> <i>v</i>:

    35  * <pre>

    36  *   for (Enumeration<E> e = v.elements(); e.hasMoreElements();)

    37  *       System.out.println(e.nextElement());</pre>

    38  * <p>

    39  * Methods are provided to enumerate through the elements of a

    40  * vector, the keys of a hashtable, and the values in a hashtable.

    41  * Enumerations are also used to specify the input streams to a

    42  * <code>SequenceInputStream</code>.

    43  * <p>

    44  * NOTE: The functionality of this interface is duplicated by the Iterator

    45  * interface.  In addition, Iterator adds an optional remove operation, and

    46  * has shorter method names.  New implementations should consider using

    47  * Iterator in preference to Enumeration.

    48  *

    49  * @see     java.util.Iterator

    50  * @see     java.io.SequenceInputStream

    51  * @see     java.util.Enumeration#nextElement()

    52  * @see     java.util.Hashtable

    53  * @see     java.util.Hashtable#elements()

    54  * @see     java.util.Hashtable#keys()

    55  * @see     java.util.Vector

    56  * @see     java.util.Vector#elements()

    57  *

    58  * @author  Lee Boynton

    59  * @since   JDK1.0

    60  */

    61 public interface Enumeration<E> {

    62     /**

    63      * Tests if this enumeration contains more elements.

    64      *

    65      * @return  <code>true</code> if and only if this enumeration object

    66      *           contains at least one more element to provide;

    67      *          <code>false</code> otherwise.

    68      */

    69     boolean hasMoreElements();

    70 

    71     /**

    72      * Returns the next element of this enumeration if this enumeration

    73      * object has at least one more element to provide.

    74      *

    75      * @return     the next element of this enumeration.

    76      * @exception  NoSuchElementException  if no more elements exist.

    77      */

    78     E nextElement();

    79 }