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 *      http://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     * @param entrySet  the entrySet to adapt
047     */
048    public EntrySetToMapIteratorAdapter(final Set<Map.Entry<K, V>> entrySet) {
049        this.entrySet = entrySet;
050        reset();
051    }
052
053    /**
054     * Gets the currently active entry.
055     * @return Map.Entry&lt;K, V&gt;
056     */
057    protected synchronized Map.Entry<K, V> current() {
058        if (entry == null) {
059            throw new IllegalStateException();
060        }
061        return entry;
062    }
063
064    /**
065     * {@inheritDoc}
066     */
067    @Override
068    public K getKey() {
069        return current().getKey();
070    }
071
072    /**
073     * {@inheritDoc}
074     */
075    @Override
076    public V getValue() {
077        return current().getValue();
078    }
079
080    /**
081     * {@inheritDoc}
082     */
083    @Override
084    public boolean hasNext() {
085        return iterator.hasNext();
086    }
087
088    /**
089     * {@inheritDoc}
090     */
091    @Override
092    public K next() {
093        entry = iterator.next();
094        return getKey();
095    }
096
097    /**
098     * {@inheritDoc}
099     */
100    @Override
101    public void remove() {
102        iterator.remove();
103        entry = null;
104    }
105
106    /**
107     * {@inheritDoc}
108     */
109    @Override
110    public synchronized void reset() {
111        iterator = entrySet.iterator();
112    }
113
114    /**
115     * {@inheritDoc}
116     */
117    @Override
118    public V setValue(final V value) {
119        return current().setValue(value);
120    }
121}