J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2006 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 iterator over a collection. {@code Iterator} takes the place of |
| 30 | * {@link Enumeration} in the Java Collections Framework. Iterators |
| 31 | * differ from enumerations in two ways: |
| 32 | * |
| 33 | * <ul> |
| 34 | * <li> Iterators allow the caller to remove elements from the |
| 35 | * underlying collection during the iteration with well-defined |
| 36 | * semantics. |
| 37 | * <li> Method names have been improved. |
| 38 | * </ul> |
| 39 | * |
| 40 | * <p>This interface is a member of the |
| 41 | * <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
| 42 | * Java Collections Framework</a>. |
| 43 | * |
| 44 | * @author Josh Bloch |
| 45 | * @see Collection |
| 46 | * @see ListIterator |
| 47 | * @see Iterable |
| 48 | * @since 1.2 |
| 49 | */ |
| 50 | public interface Iterator<E> { |
| 51 | /** |
| 52 | * Returns {@code true} if the iteration has more elements. |
| 53 | * (In other words, returns {@code true} if {@link #next} would |
| 54 | * return an element rather than throwing an exception.) |
| 55 | * |
| 56 | * @return {@code true} if the iteration has more elements |
| 57 | */ |
| 58 | boolean hasNext(); |
| 59 | |
| 60 | /** |
| 61 | * Returns the next element in the iteration. |
| 62 | * |
| 63 | * @return the next element in the iteration |
| 64 | * @throws NoSuchElementException if the iteration has no more elements |
| 65 | */ |
| 66 | E next(); |
| 67 | |
| 68 | /** |
| 69 | * Removes from the underlying collection the last element returned |
| 70 | * by this iterator (optional operation). This method can be called |
| 71 | * only once per call to {@link #next}. The behavior of an iterator |
| 72 | * is unspecified if the underlying collection is modified while the |
| 73 | * iteration is in progress in any way other than by calling this |
| 74 | * method. |
| 75 | * |
| 76 | * @throws UnsupportedOperationException if the {@code remove} |
| 77 | * operation is not supported by this iterator |
| 78 | * |
| 79 | * @throws IllegalStateException if the {@code next} method has not |
| 80 | * yet been called, or the {@code remove} method has already |
| 81 | * been called after the last call to the {@code next} |
| 82 | * method |
| 83 | */ |
| 84 | void remove(); |
| 85 | } |