001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      https://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.collections4.map;
018
019import java.util.Iterator;
020import java.util.Map;
021import java.util.Set;
022
023import org.apache.commons.collections4.MapIterator;
024import org.apache.commons.collections4.ResettableIterator;
025
026/**
027 * Adapts a Map entrySet to the MapIterator interface.
028 *
029 * @param <K> The type of the keys in the map
030 * @param <V> The type of the values in the map
031 * @since 4.0
032 */
033public class EntrySetToMapIteratorAdapter<K, V> implements MapIterator<K, V>, ResettableIterator<K> {
034
035    /** The adapted Map entry Set. */
036    final Set<Map.Entry<K, V>> entrySet;
037
038    /** The resettable iterator in use. */
039    transient Iterator<Map.Entry<K, V>> iterator;
040
041    /** The currently positioned Map entry. */
042    transient Map.Entry<K, V> entry;
043
044    /**
045     * Create a new EntrySetToMapIteratorAdapter.
046     *
047     * @param entrySet  The entrySet to adapt
048     */
049    public EntrySetToMapIteratorAdapter(final Set<Map.Entry<K, V>> entrySet) {
050        this.entrySet = entrySet;
051        reset();
052    }
053
054    /**
055     * Gets the currently active entry.
056     *
057     * @return Map.Entry&lt;K, V&gt;
058     */
059    protected synchronized Map.Entry<K, V> current() {
060        if (entry == null) {
061            throw new IllegalStateException();
062        }
063        return entry;
064    }
065
066    /**
067     * {@inheritDoc}
068     */
069    @Override
070    public K getKey() {
071        return current().getKey();
072    }
073
074    /**
075     * {@inheritDoc}
076     */
077    @Override
078    public V getValue() {
079        return current().getValue();
080    }
081
082    /**
083     * {@inheritDoc}
084     */
085    @Override
086    public boolean hasNext() {
087        return iterator.hasNext();
088    }
089
090    /**
091     * {@inheritDoc}
092     */
093    @Override
094    public K next() {
095        entry = iterator.next();
096        return getKey();
097    }
098
099    /**
100     * {@inheritDoc}
101     */
102    @Override
103    public void remove() {
104        iterator.remove();
105        entry = null;
106    }
107
108    /**
109     * {@inheritDoc}
110     */
111    @Override
112    public synchronized void reset() {
113        iterator = entrySet.iterator();
114    }
115
116    /**
117     * {@inheritDoc}
118     */
119    @Override
120    public V setValue(final V value) {
121        return current().setValue(value);
122    }
123}