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/*
* Take from Apache commons
*
* 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 com.davidbracewell.collection.trie;
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);
}