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
17 package com.google.common.collect;
18
19 import com.google.common.annotations.GwtCompatible;
20 import com.google.errorprone.annotations.CanIgnoreReturnValue;
21 import java.util.concurrent.ConcurrentMap;
22
23 /**
24 * A concurrent map which forwards all its method calls to another concurrent map. Subclasses should
25 * override one or more methods to modify the behavior of the backing map as desired per the <a
26 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
27 *
28 * <p><b>{@code default} method warning:</b> This class forwards calls to <i>only some</i> {@code
29 * default} methods. Specifically, it forwards calls only for methods that existed <a
30 * href="https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ConcurrentMap.html">before
31 * {@code default} methods were introduced</a>. For newer methods, like {@code forEach}, it inherits
32 * their default implementations. When those implementations invoke methods, they invoke methods on
33 * the {@code ForwardingConcurrentMap}.
34 *
35 * @author Charles Fry
36 * @since 2.0
37 */
38 @GwtCompatible
39 public abstract class ForwardingConcurrentMap<K, V> extends ForwardingMap<K, V>
40 implements ConcurrentMap<K, V> {
41
42 /** Constructor for use by subclasses. */
43 protected ForwardingConcurrentMap() {}
44
45 @Override
46 protected abstract ConcurrentMap<K, V> delegate();
47
48 @CanIgnoreReturnValue
49 @Override
50 public V putIfAbsent(K key, V value) {
51 return delegate().putIfAbsent(key, value);
52 }
53
54 @CanIgnoreReturnValue
55 @Override
56 public boolean remove(Object key, Object value) {
57 return delegate().remove(key, value);
58 }
59
60 @CanIgnoreReturnValue
61 @Override
62 public V replace(K key, V value) {
63 return delegate().replace(key, value);
64 }
65
66 @CanIgnoreReturnValue
67 @Override
68 public boolean replace(K key, V oldValue, V newValue) {
69 return delegate().replace(key, oldValue, newValue);
70 }
71 }