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. */ ForwardingConcurrentMap()43 protected ForwardingConcurrentMap() {} 44 45 @Override delegate()46 protected abstract ConcurrentMap<K, V> delegate(); 47 48 @CanIgnoreReturnValue 49 @Override putIfAbsent(K key, V value)50 public V putIfAbsent(K key, V value) { 51 return delegate().putIfAbsent(key, value); 52 } 53 54 @CanIgnoreReturnValue 55 @Override remove(Object key, Object value)56 public boolean remove(Object key, Object value) { 57 return delegate().remove(key, value); 58 } 59 60 @CanIgnoreReturnValue 61 @Override replace(K key, V value)62 public V replace(K key, V value) { 63 return delegate().replace(key, value); 64 } 65 66 @CanIgnoreReturnValue 67 @Override replace(K key, V oldValue, V newValue)68 public boolean replace(K key, V oldValue, V newValue) { 69 return delegate().replace(key, oldValue, newValue); 70 } 71 } 72