com.hazelcast.util.collection.ComposedKeyMap Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2017, 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.util.collection;
import java.util.HashMap;
import java.util.Map;
import static com.hazelcast.util.Preconditions.checkNotNull;
/**
* Map with a composed key.
*
* It's not thread safe and it does not allow nulls.
*
* It's biased towards use-cases where you have a smaller set of first keys.
*
* Alternative implementation could avoid map nesting and wrap keys inside
* a ComposedKey object.
*
* @param
* @param
* @param
*/
public class ComposedKeyMap {
private final Map> backingMap;
public ComposedKeyMap() {
backingMap = new HashMap>();
}
public V put(K1 key1, K2 key2, V value) {
checkNotNull(key1, "Key1 cannot be null");
checkNotNull(key2, "Key2 cannot be null");
checkNotNull(value, "Value cannot be null");
Map innerMap = backingMap.get(key1);
if (innerMap == null) {
innerMap = new HashMap();
backingMap.put(key1, innerMap);
}
return innerMap.put(key2, value);
}
public V get(K1 key1, K2 key2) {
checkNotNull(key1, "Key1 cannot be null");
checkNotNull(key2, "Key2 cannot be null");
Map innerMap = backingMap.get(key1);
if (innerMap == null) {
return null;
}
return innerMap.get(key2);
}
}