1/*
2 * Copyright (C) 2008 Google Inc.
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
21/**
22 * An empty immutable multiset.
23 *
24 * @author Jared Levy
25 */
26@GwtCompatible(serializable = true)
27final class EmptyImmutableMultiset extends ImmutableMultiset<Object> {
28  static final EmptyImmutableMultiset INSTANCE = new EmptyImmutableMultiset();
29
30  private EmptyImmutableMultiset() {
31    super(ImmutableMap.<Object, Integer>of(), 0);
32  }
33
34  Object readResolve() {
35    return INSTANCE; // preserve singleton property
36  }
37
38  private static final long serialVersionUID = 0;
39}
40