001/*
002 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
003 *
004 * Project and contact information: http://www.cascading.org/
005 *
006 * This file is part of the Cascading project.
007 *
008 * Licensed under the Apache License, Version 2.0 (the "License");
009 * you may not use this file except in compliance with the License.
010 * You may obtain a copy of the License at
011 *
012 *     http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing, software
015 * distributed under the License is distributed on an "AS IS" BASIS,
016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017 * See the License for the specific language governing permissions and
018 * limitations under the License.
019 */
020
021package cascading.util;
022
023import java.util.Collections;
024import java.util.HashMap;
025import java.util.LinkedHashSet;
026import java.util.Map;
027import java.util.Set;
028
029/**
030 *
031 */
032public class SetMultiMap<K, V> extends MultiMap<Set<V>, K, V>
033  {
034  @Override
035  protected Map<K, Set<V>> createMap()
036    {
037    return new HashMap<>();
038    }
039
040  protected Set<V> createCollection()
041    {
042    return new LinkedHashSet<>();
043    }
044
045  protected Set<V> emptyCollection()
046    {
047    return Collections.emptySet();
048    }
049  }