/* * 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; /** * Defines an iterator that operates over a Map. *

* 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. *

* 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. *

* In use, this iterator iterates through the keys in the map. After each call * to next(), the getValue() method provides direct * access to the value. The value can also be set using setValue(). *

 * MapIterator it = map.mapIterator();
 * while (it.hasNext()) {
 *   Object key = it.next();
 *   Object value = it.getValue();
 *   it.setValue(newValue);
 * }
 * 
* * @since Commons Collections 3.0 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ * * @author Stephen Colebourne */ public interface MapIterator extends Iterator { /** * Checks to see if there are more entries still to be iterated. * * @return true if the iterator has more elements */ boolean hasNext(); /** * Gets the next key from the Map. * * @return the next key in the iteration * @throws java.util.NoSuchElementException if the iteration is finished */ Object next(); //----------------------------------------------------------------------- /** * Gets the current key, which is the key returned by the last call * to next(). * * @return the current key * @throws IllegalStateException if next() has not yet been called */ Object getKey(); /** * Gets the current value, which is the value associated with the last key * returned by next(). * * @return the current value * @throws IllegalStateException if next() has not yet been called */ Object getValue(); //----------------------------------------------------------------------- /** * Removes the last returned key from the underlying Map (optional operation). *

* This method can be called once per call to next(). * * @throws UnsupportedOperationException if remove is not supported by the map * @throws IllegalStateException if next() has not yet been called * @throws IllegalStateException if remove() has already been called * since the last call to next() */ 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 next() has not yet been called * @throws IllegalStateException if remove() has been called since the * last call to next() */ Object setValue(Object value); }