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/*
 * Copyright (C) 2007 The Guava Authors
 *
 * 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.google.common.collect;

import static com.google.common.collect.CollectPreconditions.checkNonnegative;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.VisibleForTesting;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Implementation of {@code Multimap} that uses an {@code ArrayList} to store the values for a given
 * key. A {@link HashMap} associates each key with an {@link ArrayList} of values.
 *
 * 

When iterating through the collections supplied by this class, the ordering of values for a * given key agrees with the order in which the values were added. * *

This multimap allows duplicate key-value pairs. After adding a new key-value pair equal to an * existing key-value pair, the {@code ArrayListMultimap} will contain entries for both the new * value and the old value. * *

Keys and values may be null. All optional multimap methods are supported, and all returned * views are modifiable. * *

The lists returned by {@link #get}, {@link #removeAll}, and {@link #replaceValues} all * implement {@link java.util.RandomAccess}. * *

This class is not threadsafe when any concurrent operations update the multimap. Concurrent * read operations will work correctly. To allow concurrent update operations, wrap your multimap * with a call to {@link Multimaps#synchronizedListMultimap}. * *

See the Guava User Guide article on {@code * Multimap}. * * @author Jared Levy * @since 2.0 */ @GwtCompatible(serializable = true, emulated = true) public final class ArrayListMultimap extends ArrayListMultimapGwtSerializationDependencies { // Default from ArrayList private static final int DEFAULT_VALUES_PER_KEY = 3; @VisibleForTesting transient int expectedValuesPerKey; /** * Creates a new, empty {@code ArrayListMultimap} with the default initial capacities. * *

This method will soon be deprecated in favor of {@code * MultimapBuilder.hashKeys().arrayListValues().build()}. */ public static ArrayListMultimap create() { return new ArrayListMultimap<>(); } /** * Constructs an empty {@code ArrayListMultimap} with enough capacity to hold the specified * numbers of keys and values without resizing. * *

This method will soon be deprecated in favor of {@code * MultimapBuilder.hashKeys(expectedKeys).arrayListValues(expectedValuesPerKey).build()}. * * @param expectedKeys the expected number of distinct keys * @param expectedValuesPerKey the expected average number of values per key * @throws IllegalArgumentException if {@code expectedKeys} or {@code expectedValuesPerKey} is * negative */ public static ArrayListMultimap create(int expectedKeys, int expectedValuesPerKey) { return new ArrayListMultimap<>(expectedKeys, expectedValuesPerKey); } /** * Constructs an {@code ArrayListMultimap} with the same mappings as the specified multimap. * *

This method will soon be deprecated in favor of {@code * MultimapBuilder.hashKeys().arrayListValues().build(multimap)}. * * @param multimap the multimap whose contents are copied to this multimap */ public static ArrayListMultimap create(Multimap multimap) { return new ArrayListMultimap<>(multimap); } private ArrayListMultimap() { this(12, DEFAULT_VALUES_PER_KEY); } private ArrayListMultimap(int expectedKeys, int expectedValuesPerKey) { super(Platform.>newHashMapWithExpectedSize(expectedKeys)); checkNonnegative(expectedValuesPerKey, "expectedValuesPerKey"); this.expectedValuesPerKey = expectedValuesPerKey; } private ArrayListMultimap(Multimap multimap) { this( multimap.keySet().size(), (multimap instanceof ArrayListMultimap) ? ((ArrayListMultimap) multimap).expectedValuesPerKey : DEFAULT_VALUES_PER_KEY); putAll(multimap); } /** * Creates a new, empty {@code ArrayList} to hold the collection of values for an arbitrary key. */ @Override List createCollection() { return new ArrayList(expectedValuesPerKey); } /** * Reduces the memory used by this {@code ArrayListMultimap}, if feasible. * * @deprecated For a {@link ListMultimap} that automatically trims to size, use {@link * ImmutableListMultimap}. If you need a mutable collection, remove the {@code trimToSize} * call, or switch to a {@code HashMap>}. */ @Deprecated public void trimToSize() { for (Collection collection : backingMap().values()) { ArrayList arrayList = (ArrayList) collection; arrayList.trimToSize(); } } /** * @serialData expectedValuesPerKey, number of distinct keys, and then for each distinct key: the * key, number of values for that key, and the key's values */ @GwtIncompatible // java.io.ObjectOutputStream private void writeObject(ObjectOutputStream stream) throws IOException { stream.defaultWriteObject(); Serialization.writeMultimap(this, stream); } @GwtIncompatible // java.io.ObjectOutputStream private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException { stream.defaultReadObject(); expectedValuesPerKey = DEFAULT_VALUES_PER_KEY; int distinctKeys = Serialization.readCount(stream); Map> map = CompactHashMap.create(); setMap(map); Serialization.populateMultimap(this, stream, distinctKeys); } @GwtIncompatible // Not needed in emulated source. private static final long serialVersionUID = 0; }





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