com.hazelcast.internal.util.collection.InternalSetMultimap Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2020, Hazelcast, Inc. All Rights Reserved.
*
* 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 com.hazelcast.internal.util.collection;
import com.hazelcast.multimap.MultiMap;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import static com.hazelcast.internal.util.Preconditions.checkNotNull;
/**
* Simplistic implementation of MultiMap.
* It's not thread-safe, concurrent access has to be externally synchronized.
*
* It does not allow duplicates: The same value can be associated with the same key once only. Duplicates are
* eliminated.
*
* The name has a prefix Internal- to avoid confusion with {@link MultiMap}
*
* @param
* @param
*/
public class InternalSetMultimap {
private final Map> backingMap;
public InternalSetMultimap() {
this.backingMap = new HashMap>();
}
/**
* Associate value to a given key. It has no effect if the value is already associated with the key.
*
* @param key
* @param value
*/
public void put(K key, V value) {
checkNotNull(key, "Key cannot be null");
checkNotNull(value, "Value cannot be null");
Set values = backingMap.get(key);
if (values == null) {
values = new HashSet();
backingMap.put(key, values);
}
values.add(value);
}
/**
* Return Set of values associated with a given key
*
* @param key
* @return
*/
public Set get(K key) {
checkNotNull(key, "Key cannot be null");
return backingMap.get(key);
}
public Set>> entrySet() {
return backingMap.entrySet();
}
}