com.groupbyinc.common.apache.commons.collections4.ListValuedMap Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.collections4;
import java.util.List;
/**
* Defines a map that holds a list of values against each key.
*
* A {@code ListValuedMap} is a Map with slightly different semantics:
*
* - Putting a value into the map will add the value to a {@link List} at that key.
* - Getting a value will return a {@link List}, holding all the values put to that key.
*
*
* @since 4.1
* @version $Id: ListValuedMap.java 1685299 2015-06-13 18:27:11Z tn $
*/
public interface ListValuedMap extends MultiValuedMap {
/**
* Gets the list of values associated with the specified key.
*
* This method will return an empty list if
* {@link #containsKey(Object)} returns {@code false}. Changes to the
* returned list will update the underlying {@code ListValuedMap} and
* vice-versa.
*
* @param key the key to retrieve
* @return the {@code List} of values, implementations should return an
* empty {@code List} for no mapping
* @throws NullPointerException if the key is null and null keys are invalid
*/
@Override
List get(K key);
/**
* Removes all values associated with the specified key.
*
* The returned list may be modifiable, but updates will not be
* propagated to this list-valued map. In case no mapping was stored for the
* specified key, an empty, unmodifiable list will be returned.
*
* @param key the key to remove values from
* @return the {@code List} of values removed, implementations
* typically return an empty, unmodifiable {@code List} for no mapping found
* @throws UnsupportedOperationException if the map is unmodifiable
* @throws NullPointerException if the key is null and null keys are invalid
*/
@Override
List remove(Object key);
}