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 *
032 * @since 4.0
033 */
034public class EntrySetToMapIteratorAdapter<K, V> implements MapIterator<K, V>, ResettableIterator<K> {
035
036    /** The adapted Map entry Set. */
037    final Set<Map.Entry<K, V>> entrySet;
038
039    /** The resettable iterator in use. */
040    transient Iterator<Map.Entry<K, V>> iterator;
041
042    /** The currently positioned Map entry. */
043    transient Map.Entry<K, V> entry;
044
045    /**
046     * Create a new EntrySetToMapIteratorAdapter.
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     * @return Map.Entry&lt;K, V&gt;
057     */
058    protected synchronized Map.Entry<K, V> current() {
059        if (entry == null) {
060            throw new IllegalStateException();
061        }
062        return entry;
063    }
064
065    /**
066     * {@inheritDoc}
067     */
068    @Override
069    public K getKey() {
070        return current().getKey();
071    }
072
073    /**
074     * {@inheritDoc}
075     */
076    @Override
077    public V getValue() {
078        return current().getValue();
079    }
080
081    /**
082     * {@inheritDoc}
083     */
084    @Override
085    public boolean hasNext() {
086        return iterator.hasNext();
087    }
088
089    /**
090     * {@inheritDoc}
091     */
092    @Override
093    public K next() {
094        entry = iterator.next();
095        return getKey();
096    }
097
098    /**
099     * {@inheritDoc}
100     */
101    @Override
102    public void remove() {
103        iterator.remove();
104        entry = null;
105    }
106
107    /**
108     * {@inheritDoc}
109     */
110    @Override
111    public synchronized void reset() {
112        iterator = entrySet.iterator();
113    }
114
115    /**
116     * {@inheritDoc}
117     */
118    @Override
119    public V setValue(final V value) {
120        return current().setValue(value);
121    }
122}