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.iterators;
018
019import org.apache.commons.collections4.MapIterator;
020import org.apache.commons.collections4.Unmodifiable;
021
022/**
023 * Decorates a map iterator such that it cannot be modified.
024 * <p>
025 * Attempts to modify it will result in an UnsupportedOperationException.
026 *
027 * @since 3.0
028 * @version $Id: UnmodifiableMapIterator.html 972421 2015-11-14 20:00:04Z tn $
029 */
030public final class UnmodifiableMapIterator<K, V> implements MapIterator<K, V>, Unmodifiable {
031
032    /** The iterator being decorated */
033    private final MapIterator<? extends K, ? extends V> iterator;
034
035    //-----------------------------------------------------------------------
036    /**
037     * Decorates the specified iterator such that it cannot be modified.
038     *
039     * @param <K>  the key type
040     * @param <V>  the value type
041     * @param iterator  the iterator to decorate
042     * @return a new unmodifiable map iterator
043     * @throws IllegalArgumentException if the iterator is null
044     */
045    public static <K, V> MapIterator<K, V> unmodifiableMapIterator(
046            final MapIterator<? extends K, ? extends V> iterator) {
047        if (iterator == null) {
048            throw new IllegalArgumentException("MapIterator must not be null");
049        }
050        if (iterator instanceof Unmodifiable) {
051            @SuppressWarnings("unchecked") // safe to upcast
052            final MapIterator<K, V> tmpIterator = (MapIterator<K, V>) iterator;
053            return tmpIterator;
054        }
055        return new UnmodifiableMapIterator<K, V>(iterator);
056    }
057
058    //-----------------------------------------------------------------------
059    /**
060     * Constructor.
061     *
062     * @param iterator  the iterator to decorate
063     */
064    private UnmodifiableMapIterator(final MapIterator<? extends K, ? extends V> iterator) {
065        super();
066        this.iterator = iterator;
067    }
068
069    //-----------------------------------------------------------------------
070    public boolean hasNext() {
071        return iterator.hasNext();
072    }
073
074    public K next() {
075        return iterator.next();
076    }
077
078    public K getKey() {
079        return iterator.getKey();
080    }
081
082    public V getValue() {
083        return iterator.getValue();
084    }
085
086    public V setValue(final V value) {
087        throw new UnsupportedOperationException("setValue() is not supported");
088    }
089
090    public void remove() {
091        throw new UnsupportedOperationException("remove() is not supported");
092    }
093
094}