1/*
2 * Copyright (C) 2007 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.collect;
18
19import com.google.common.annotations.GwtCompatible;
20
21import java.util.LinkedHashMap;
22
23/**
24 * A {@code Multiset} implementation with predictable iteration order. Its
25 * iterator orders elements according to when the first occurrence of the
26 * element was added. When the multiset contains multiple instances of an
27 * element, those instances are consecutive in the iteration order. If all
28 * occurrences of an element are removed, after which that element is added to
29 * the multiset, the element will appear at the end of the iteration.
30 *
31 * @author Kevin Bourrillion
32 * @author Jared Levy
33 * @since 2.0 (imported from Google Collections Library)
34 */
35@GwtCompatible(serializable = true, emulated = true)
36@SuppressWarnings("serial") // we're overriding default serialization
37public final class LinkedHashMultiset<E> extends AbstractMapBasedMultiset<E> {
38
39  /**
40   * Creates a new, empty {@code LinkedHashMultiset} using the default initial
41   * capacity.
42   */
43  public static <E> LinkedHashMultiset<E> create() {
44    return new LinkedHashMultiset<E>();
45  }
46
47  /**
48   * Creates a new, empty {@code LinkedHashMultiset} with the specified expected
49   * number of distinct elements.
50   *
51   * @param distinctElements the expected number of distinct elements
52   * @throws IllegalArgumentException if {@code distinctElements} is negative
53   */
54  public static <E> LinkedHashMultiset<E> create(int distinctElements) {
55    return new LinkedHashMultiset<E>(distinctElements);
56  }
57
58  /**
59   * Creates a new {@code LinkedHashMultiset} containing the specified elements.
60   *
61   * <p>This implementation is highly efficient when {@code elements} is itself
62   * a {@link Multiset}.
63   *
64   * @param elements the elements that the multiset should contain
65   */
66  public static <E> LinkedHashMultiset<E> create(
67      Iterable<? extends E> elements) {
68    LinkedHashMultiset<E> multiset =
69        create(Multisets.inferDistinctElements(elements));
70    Iterables.addAll(multiset, elements);
71    return multiset;
72  }
73
74  private LinkedHashMultiset() {
75    super(new LinkedHashMap<E, Count>());
76  }
77
78  private LinkedHashMultiset(int distinctElements) {
79    // Could use newLinkedHashMapWithExpectedSize() if it existed
80    super(new LinkedHashMap<E, Count>(Maps.capacity(distinctElements)));
81  }
82}
83
84