001/* 002 * Copyright (C) 2007 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package com.google.common.collect; 018 019import com.google.common.annotations.GwtCompatible; 020import com.google.errorprone.annotations.CanIgnoreReturnValue; 021import java.util.concurrent.ConcurrentMap; 022 023/** 024 * A concurrent map which forwards all its method calls to another concurrent map. Subclasses should 025 * override one or more methods to modify the behavior of the backing map as desired per the <a 026 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>. 027 * 028 * <p><b>{@code default} method warning:</b> This class forwards calls to <i>only some</i> {@code 029 * default} methods. Specifically, it forwards calls only for methods that existed <a 030 * href="https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ConcurrentMap.html">before 031 * {@code default} methods were introduced</a>. For newer methods, like {@code forEach}, it inherits 032 * their default implementations. When those implementations invoke methods, they invoke methods on 033 * the {@code ForwardingConcurrentMap}. 034 * 035 * @author Charles Fry 036 * @since 2.0 037 */ 038@GwtCompatible 039public abstract class ForwardingConcurrentMap<K, V> extends ForwardingMap<K, V> 040 implements ConcurrentMap<K, V> { 041 042 /** Constructor for use by subclasses. */ 043 protected ForwardingConcurrentMap() {} 044 045 @Override 046 protected abstract ConcurrentMap<K, V> delegate(); 047 048 @CanIgnoreReturnValue 049 @Override 050 public V putIfAbsent(K key, V value) { 051 return delegate().putIfAbsent(key, value); 052 } 053 054 @CanIgnoreReturnValue 055 @Override 056 public boolean remove(Object key, Object value) { 057 return delegate().remove(key, value); 058 } 059 060 @CanIgnoreReturnValue 061 @Override 062 public V replace(K key, V value) { 063 return delegate().replace(key, value); 064 } 065 066 @CanIgnoreReturnValue 067 @Override 068 public boolean replace(K key, V oldValue, V newValue) { 069 return delegate().replace(key, oldValue, newValue); 070 } 071}