    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;
    018
    019import java.util.Comparator;
    020import java.util.SortedMap;
    021
    022/**
    023 * Defines a map that allows bidirectional lookup between key and values
    024 * and retains both keys and values in sorted order.
    025 * <p>
    026 * Implementations should allow a value to be looked up from a key and
    027 * a key to be looked up from a value with equal performance.
    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 3.0
    032 */
    033public interface SortedBidiMap<K, V> extends OrderedBidiMap<K, V>, SortedMap<K, V> {
    034
    035    /**
    036     * Gets a view of this map where the keys and values are reversed.
    037     * <p>
    038     * Changes to one map will be visible in the other and vice versa.
    039     * This enables both directions of the map to be accessed equally.
    040     * <p>
    041     * Implementations should seek to avoid creating a new object every time this
    042     * method is called. See <code>AbstractMap.values()</code> etc. Calling this
    043     * method on the inverse map should return the original.
    044     * <p>
    045     * Implementations must return a <code>SortedBidiMap</code> instance,
    046     * usually by forwarding to <code>inverseSortedBidiMap()</code>.
    047     *
    048     * @return an inverted bidirectional map
    049     */
    050    @Override
    051    SortedBidiMap<V, K> inverseBidiMap();
    052
    053    /**
    054     * Get the comparator used for the values in the value-to-key map aspect.
    055     * @return Comparator&lt;? super V&gt;
    056     */
    057    Comparator<? super V> valueComparator();
    058}