/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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 org.apache.commons.collections4.multimap;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.Map;
  
  import org.apache.commons.collections4.MultiValuedMap;
  
  /**
   * Implements a {@code ListValuedMap}, using a {@link HashMap} to provide data
   * storage and {@link ArrayList}s as value collections. This is the standard
   * implementation of a ListValuedMap.
   * <p>
   * <strong>Note that ArrayListValuedHashMap is not synchronized and is not
   * thread-safe.</strong> If you wish to use this map from multiple threads
   * concurrently, you must use appropriate synchronization. This class may throw
   * exceptions when accessed by concurrent threads without synchronization.
   * </p>
   *
   * @param <K> the type of the keys in this map
   * @param <V> the type of the values in this map
   * @since 4.1
   */
  public class ArrayListValuedHashMap<K, V> extends AbstractListValuedMap<K, V>
      implements Serializable {
  
      /** Serialization Version */
      private static final long serialVersionUID = 20151118L;
  
      /**
       * The initial map capacity used when none specified in constructor.
       */
      private static final int DEFAULT_INITIAL_MAP_CAPACITY = 16;
  
      /**
       * The initial list capacity when using none specified in constructor.
       */
      private static final int DEFAULT_INITIAL_LIST_CAPACITY = 3;
  
      /**
       * The initial list capacity when creating a new value collection.
       */
      private final int initialListCapacity;
  
      /**
       * Creates an empty ArrayListValuedHashMap with the default initial
       * map capacity (16) and the default initial list capacity (3).
       */
      public ArrayListValuedHashMap() {
          this(DEFAULT_INITIAL_MAP_CAPACITY, DEFAULT_INITIAL_LIST_CAPACITY);
      }
  
      /**
       * Creates an empty ArrayListValuedHashMap with the default initial
       * map capacity (16) and the specified initial list capacity.
       *
       * @param initialListCapacity  the initial capacity used for value collections
       */
      public ArrayListValuedHashMap(final int initialListCapacity) {
          this(DEFAULT_INITIAL_MAP_CAPACITY, initialListCapacity);
      }
  
      /**
       * Creates an empty ArrayListValuedHashMap with the specified initial
       * map and list capacities.
       *
       * @param initialMapCapacity  the initial hashmap capacity
       * @param initialListCapacity  the initial capacity used for value collections
       */
      public ArrayListValuedHashMap(final int initialMapCapacity, final int initialListCapacity) {
          super(new HashMap<>(initialMapCapacity));
          this.initialListCapacity = initialListCapacity;
      }
  
      /**
       * Creates an ArrayListValuedHashMap copying all the mappings of the given map.
       *
       * @param map a {@code Map} to copy into this map
      */
     public ArrayListValuedHashMap(final Map<? extends K, ? extends V> map) {
         this(map.size(), DEFAULT_INITIAL_LIST_CAPACITY);
         super.putAll(map);
     }
 
     /**
      * Creates an ArrayListValuedHashMap copying all the mappings of the given map.
      *
      * @param map a {@code MultiValuedMap} to copy into this map
      */
     public ArrayListValuedHashMap(final MultiValuedMap<? extends K, ? extends V> map) {
         this(map.size(), DEFAULT_INITIAL_LIST_CAPACITY);
         super.putAll(map);
     }
 
     @Override
     protected ArrayList<V> createCollection() {
         return new ArrayList<>(initialListCapacity);
     }
 
     /**
      * Deserializes an instance from an ObjectInputStream.
      *
      * @param in The source ObjectInputStream.
      * @throws IOException            Any of the usual Input/Output related exceptions.
      * @throws ClassNotFoundException A class of a serialized object cannot be found.
      */
     private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
         in.defaultReadObject();
         setMap(new HashMap<>());
         doReadObject(in);
     }
 
     /**
      * Trims the capacity of all value collections to their current size.
      */
     public void trimToSize() {
         for (final Collection<V> coll : getMap().values()) {
             final ArrayList<V> list = (ArrayList<V>) coll;
             list.trimToSize();
         }
     }
 
     /**
      * Serializes this object to an ObjectOutputStream.
      *
      * @param out the target ObjectOutputStream.
      * @throws IOException thrown when an I/O errors occur writing to the target stream.
      */
     private void writeObject(final ObjectOutputStream out) throws IOException {
         out.defaultWriteObject();
         doWriteObject(out);
     }
 
 }