MultiMap.java
- /*
- * *************************************************************************************************************************************************************
- *
- * TheseFoolishThings: Miscellaneous utilities
- * http://tidalwave.it/projects/thesefoolishthings
- *
- * Copyright (C) 2009 - 2025 by Tidalwave s.a.s. (http://tidalwave.it)
- *
- * *************************************************************************************************************************************************************
- *
- * 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.
- *
- * *************************************************************************************************************************************************************
- *
- * git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
- * git clone https://github.com/tidalwave-it/thesefoolishthings-src
- *
- * *************************************************************************************************************************************************************
- */
- package it.tidalwave.util.impl;
- import jakarta.annotation.Nonnull;
- import java.util.Collection;
- import java.util.Collections;
- import java.util.HashMap;
- import java.util.HashSet;
- import java.util.Set;
- /***************************************************************************************************************************************************************
- *
- * @author Fabrizio Giudici
- *
- **************************************************************************************************************************************************************/
- public class MultiMap<K, V> extends HashMap<K, Set<V>>
- {
- private static final long serialVersionUID = 8834342771135005212L;
- public synchronized void add (@Nonnull final K key, @Nonnull final V value)
- {
- internalGetValues(key).add(value);
- }
- public synchronized void addAll (@Nonnull final K key, @Nonnull final Collection<? extends V> values)
- {
- if (!values.isEmpty())
- {
- internalGetValues(key).addAll(values);
- }
- }
- @Nonnull
- public synchronized Set<V> getValues (@Nonnull final K key)
- {
- final var values = get(key);
- return (values == null) ? Collections.emptySet() : Collections.unmodifiableSet(values);
- }
- @Nonnull
- private Set<V> internalGetValues (@Nonnull final K key)
- {
- var values = get(key);
- if (values == null)
- {
- values = new HashSet<>();
- put(key, values);
- }
- return values;
- }
- }