| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.collections; |
| |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| |
| /** |
| * Defines an iterator that operates over a <code>Map</code>. |
| * <p> |
| * This iterator is a special version designed for maps. It can be more |
| * efficient to use this rather than an entry set iterator where the option |
| * is available, and it is certainly more convenient. |
| * <p> |
| * A map that provides this interface may not hold the data internally using |
| * Map Entry objects, thus this interface can avoid lots of object creation. |
| * <p> |
| * In use, this iterator iterates through the keys in the map. After each call |
| * to <code>next()</code>, the <code>getValue()</code> method provides direct |
| * access to the value. The value can also be set using <code>setValue()</code>. |
| * <pre> |
| * MapIterator<String,Integer> it = map.mapIterator(); |
| * while (it.hasNext()) { |
| * String key = it.next(); |
| * Integer value = it.getValue(); |
| * it.setValue(value + 1); |
| * } |
| * </pre> |
| * |
| * @param <K> the type of the keys in the map |
| * @param <V> the type of the values in the map |
| * @since Commons Collections 3.0 |
| * @version $Revision$ $Date$ |
| * |
| * @author Stephen Colebourne |
| */ |
| public interface MapIterator<K, V> extends Iterator<K> { |
| |
| /** |
| * Checks to see if there are more entries still to be iterated. |
| * |
| * @return <code>true</code> if the iterator has more elements |
| */ |
| boolean hasNext(); |
| |
| /** |
| * Gets the next <em>key</em> from the <code>Map</code>. |
| * |
| * @return the next key in the iteration |
| * @throws NoSuchElementException if the iteration is finished |
| */ |
| K next(); |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Gets the current key, which is the key returned by the last call |
| * to <code>next()</code>. |
| * |
| * @return the current key |
| * @throws IllegalStateException if <code>next()</code> has not yet been called |
| */ |
| K getKey(); |
| |
| /** |
| * Gets the current value, which is the value associated with the last key |
| * returned by <code>next()</code>. |
| * |
| * @return the current value |
| * @throws IllegalStateException if <code>next()</code> has not yet been called |
| */ |
| V getValue(); |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Removes the last returned key from the underlying <code>Map</code> (optional operation). |
| * <p> |
| * This method can be called once per call to <code>next()</code>. |
| * |
| * @throws UnsupportedOperationException if remove is not supported by the map |
| * @throws IllegalStateException if <code>next()</code> has not yet been called |
| * @throws IllegalStateException if <code>remove()</code> has already been called |
| * since the last call to <code>next()</code> |
| */ |
| void remove(); |
| |
| /** |
| * Sets the value associated with the current key (optional operation). |
| * |
| * @param value the new value |
| * @return the previous value |
| * @throws UnsupportedOperationException if setValue is not supported by the map |
| * @throws IllegalStateException if <code>next()</code> has not yet been called |
| * @throws IllegalStateException if <code>remove()</code> has been called since the |
| * last call to <code>next()</code> |
| */ |
| V setValue(V value); |
| |
| } |