/*
* Copyright 2002-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.util;
import java.util.List;
import java.util.Map;
/**
* Extension of the {@code Map} interface that stores multiple values.
*
* @author Arjen Poutsma
* @since 3.0
*/
public interface MultiValueMap<K, V> extends Map<K, List<V>> {
/**
* Return the first value for the given key.
* @param key the key
* @return the first value for the specified key, or {@code null}
*/
V getFirst(K key);
/**
* Add the given single value to the current list of values for the given key.
* @param key the key
* @param value the value to be added
*/
void add(K key, V value);
/**
* Add all the values of the given list to the current list of values for the given key.
* @param key they key
* @param values the values to be added
* @since 5.0
*/
void addAll(K key, List<V> values);
/**
* Set the given single value under the given key.
* @param key the key
* @param value the value to set
*/
void set(K key, V value);
/**
* Set the given values under.
* @param values the values.
*/
void setAll(Map<K, V> values);
/**
* Returns the first values contained in this {@code MultiValueMap}.
* @return a single value representation of this map
*/
Map<K, V> toSingleValueMap();
}