001/* 002 * Copyright (C) 2011 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.util.concurrent; 016 017import com.google.common.annotations.GwtIncompatible; 018import java.util.concurrent.Callable; 019import org.checkerframework.checker.nullness.qual.Nullable; 020 021/** 022 * A listening executor service which forwards all its method calls to another listening executor 023 * service. Subclasses should override one or more methods to modify the behavior of the backing 024 * executor service as desired per the <a 025 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>. 026 * 027 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code 028 * default} methods. Instead, it inherits their default implementations. When those implementations 029 * invoke methods, they invoke methods on the {@code ForwardingListeningExecutorService}. 030 * 031 * @author Isaac Shum 032 * @since 10.0 033 */ 034@GwtIncompatible 035@ElementTypesAreNonnullByDefault 036public abstract class ForwardingListeningExecutorService extends ForwardingExecutorService 037 implements ListeningExecutorService { 038 /** Constructor for use by subclasses. */ 039 protected ForwardingListeningExecutorService() {} 040 041 @Override 042 protected abstract ListeningExecutorService delegate(); 043 044 @Override 045 public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) { 046 return delegate().submit(task); 047 } 048 049 @Override 050 public ListenableFuture<?> submit(Runnable task) { 051 return delegate().submit(task); 052 } 053 054 @Override 055 public <T extends @Nullable Object> ListenableFuture<T> submit( 056 Runnable task, @ParametricNullness T result) { 057 return delegate().submit(task, result); 058 } 059}