001/*
002 * Copyright 2002-2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.util;
018
019import java.util.List;
020import java.util.Map;
021
022/**
023 * Extension of the {@code Map} interface that stores multiple values.
024 *
025 * @author Arjen Poutsma
026 * @since 3.0
027 * @param <K> the key type
028 * @param <V> the value element type
029 */
030public interface MultiValueMap<K, V> extends Map<K, List<V>> {
031
032        /**
033         * Return the first value for the given key.
034         * @param key the key
035         * @return the first value for the specified key, or {@code null} if none
036         */
037        V getFirst(K key);
038
039        /**
040         * Add the given single value to the current list of values for the given key.
041         * @param key the key
042         * @param value the value to be added
043         */
044        void add(K key, V value);
045
046        /**
047         * Set the given single value under the given key.
048         * @param key the key
049         * @param value the value to set
050         */
051        void set(K key, V value);
052
053        /**
054         * Set the given values under.
055         * @param values the values.
056         */
057        void setAll(Map<K, V> values);
058
059        /**
060         * Return a {@code Map} with the first values contained in this {@code MultiValueMap}.
061         * @return a single value representation of this map
062         */
063        Map<K, V> toSingleValueMap();
064
065}