    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 */
    029public final class UnmodifiableMapIterator<K, V> implements MapIterator<K, V>, Unmodifiable {
    030
    031    /** The iterator being decorated */
    032    private final MapIterator<? extends K, ? extends V> iterator;
    033
    034    //-----------------------------------------------------------------------
    035    /**
    036     * Decorates the specified iterator such that it cannot be modified.
    037     *
    038     * @param <K>  the key type
    039     * @param <V>  the value type
    040     * @param iterator  the iterator to decorate
    041     * @return a new unmodifiable map iterator
    042     * @throws NullPointerException if the iterator is null
    043     */
    044    public static <K, V> MapIterator<K, V> unmodifiableMapIterator(
    045            final MapIterator<? extends K, ? extends V> iterator) {
    046        if (iterator == null) {
    047            throw new NullPointerException("MapIterator must not be null");
    048        }
    049        if (iterator instanceof Unmodifiable) {
    050            @SuppressWarnings("unchecked") // safe to upcast
    051            final MapIterator<K, V> tmpIterator = (MapIterator<K, V>) iterator;
    052            return tmpIterator;
    053        }
    054        return new UnmodifiableMapIterator<>(iterator);
    055    }
    056
    057    //-----------------------------------------------------------------------
    058    /**
    059     * Constructor.
    060     *
    061     * @param iterator  the iterator to decorate
    062     */
    063    private UnmodifiableMapIterator(final MapIterator<? extends K, ? extends V> iterator) {
    064        super();
    065        this.iterator = iterator;
    066    }
    067
    068    //-----------------------------------------------------------------------
    069    @Override
    070    public boolean hasNext() {
    071        return iterator.hasNext();
    072    }
    073
    074    @Override
    075    public K next() {
    076        return iterator.next();
    077    }
    078
    079    @Override
    080    public K getKey() {
    081        return iterator.getKey();
    082    }
    083
    084    @Override
    085    public V getValue() {
    086        return iterator.getValue();
    087    }
    088
    089    @Override
    090    public V setValue(final V value) {
    091        throw new UnsupportedOperationException("setValue() is not supported");
    092    }
    093
    094    @Override
    095    public void remove() {
    096        throw new UnsupportedOperationException("remove() is not supported");
    097    }
    098
    099}