001/* 002 * Copyright (c) 2007-2016 Concurrent, 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 }