01: /*
02: * Copyright 1994-2005 Sun Microsystems, Inc. All Rights Reserved.
03: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
04: *
05: * This code is free software; you can redistribute it and/or modify it
06: * under the terms of the GNU General Public License version 2 only, as
07: * published by the Free Software Foundation. Sun designates this
08: * particular file as subject to the "Classpath" exception as provided
09: * 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<E></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: * @version 1.30, 05/05/07
60: * @since JDK1.0
61: */
62: public interface Enumeration<E> {
63: /**
64: * Tests if this enumeration contains more elements.
65: *
66: * @return <code>true</code> if and only if this enumeration object
67: * contains at least one more element to provide;
68: * <code>false</code> otherwise.
69: */
70: boolean hasMoreElements();
71:
72: /**
73: * Returns the next element of this enumeration if this enumeration
74: * object has at least one more element to provide.
75: *
76: * @return the next element of this enumeration.
77: * @exception NoSuchElementException if no more elements exist.
78: */
79: E nextElement();
80: }
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