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/*
 * 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.collections4;

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()) {
 *   String key = it.next();
 *   Integer value = it.getValue();
 *   it.setValue(value + 1);
 * }
 * 
* * @param the type of the keys in the map * @param the type of the values in the map * @since 3.0 * @version $Id: MapIterator.java 1469004 2013-04-17 17:37:03Z tn $ */ 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 */ K 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 */ K 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 */ V 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() */ V setValue(V value); }





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