Shuyi Chen | d7955ce | 2013-05-22 14:51:55 -0700 | [diff] [blame] | 1 | // GenericsNote: Converted. |
| 2 | /* |
| 3 | * Copyright 2003-2004 The Apache Software Foundation |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | * you may not use this file except in compliance with the License. |
| 7 | * You may obtain a copy of the License at |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | */ |
| 17 | package org.jivesoftware.smack.util.collections; |
| 18 | |
| 19 | import java.util.Iterator; |
| 20 | |
| 21 | /** |
| 22 | * Defines an iterator that operates over a <code>Map</code>. |
| 23 | * <p/> |
| 24 | * This iterator is a special version designed for maps. It can be more |
| 25 | * efficient to use this rather than an entry set iterator where the option |
| 26 | * is available, and it is certainly more convenient. |
| 27 | * <p/> |
| 28 | * A map that provides this interface may not hold the data internally using |
| 29 | * Map Entry objects, thus this interface can avoid lots of object creation. |
| 30 | * <p/> |
| 31 | * In use, this iterator iterates through the keys in the map. After each call |
| 32 | * to <code>next()</code>, the <code>getValue()</code> method provides direct |
| 33 | * access to the value. The value can also be set using <code>setValue()</code>. |
| 34 | * <pre> |
| 35 | * MapIterator it = map.mapIterator(); |
| 36 | * while (it.hasNext()) { |
| 37 | * Object key = it.next(); |
| 38 | * Object value = it.getValue(); |
| 39 | * it.setValue(newValue); |
| 40 | * } |
| 41 | * </pre> |
| 42 | * |
| 43 | * @author Matt Hall, John Watkinson, Stephen Colebourne |
| 44 | * @version $Revision: 1.1 $ $Date: 2005/10/11 17:05:19 $ |
| 45 | * @since Commons Collections 3.0 |
| 46 | */ |
| 47 | public interface MapIterator <K,V> extends Iterator<K> { |
| 48 | |
| 49 | /** |
| 50 | * Checks to see if there are more entries still to be iterated. |
| 51 | * |
| 52 | * @return <code>true</code> if the iterator has more elements |
| 53 | */ |
| 54 | boolean hasNext(); |
| 55 | |
| 56 | /** |
| 57 | * Gets the next <em>key</em> from the <code>Map</code>. |
| 58 | * |
| 59 | * @return the next key in the iteration |
| 60 | * @throws java.util.NoSuchElementException |
| 61 | * if the iteration is finished |
| 62 | */ |
| 63 | K next(); |
| 64 | |
| 65 | //----------------------------------------------------------------------- |
| 66 | /** |
| 67 | * Gets the current key, which is the key returned by the last call |
| 68 | * to <code>next()</code>. |
| 69 | * |
| 70 | * @return the current key |
| 71 | * @throws IllegalStateException if <code>next()</code> has not yet been called |
| 72 | */ |
| 73 | K getKey(); |
| 74 | |
| 75 | /** |
| 76 | * Gets the current value, which is the value associated with the last key |
| 77 | * returned by <code>next()</code>. |
| 78 | * |
| 79 | * @return the current value |
| 80 | * @throws IllegalStateException if <code>next()</code> has not yet been called |
| 81 | */ |
| 82 | V getValue(); |
| 83 | |
| 84 | //----------------------------------------------------------------------- |
| 85 | /** |
| 86 | * Removes the last returned key from the underlying <code>Map</code> (optional operation). |
| 87 | * <p/> |
| 88 | * This method can be called once per call to <code>next()</code>. |
| 89 | * |
| 90 | * @throws UnsupportedOperationException if remove is not supported by the map |
| 91 | * @throws IllegalStateException if <code>next()</code> has not yet been called |
| 92 | * @throws IllegalStateException if <code>remove()</code> has already been called |
| 93 | * since the last call to <code>next()</code> |
| 94 | */ |
| 95 | void remove(); |
| 96 | |
| 97 | /** |
| 98 | * Sets the value associated with the current key (optional operation). |
| 99 | * |
| 100 | * @param value the new value |
| 101 | * @return the previous value |
| 102 | * @throws UnsupportedOperationException if setValue is not supported by the map |
| 103 | * @throws IllegalStateException if <code>next()</code> has not yet been called |
| 104 | * @throws IllegalStateException if <code>remove()</code> has been called since the |
| 105 | * last call to <code>next()</code> |
| 106 | */ |
| 107 | V setValue(V value); |
| 108 | |
| 109 | } |