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 com.google.common.annotations.J2ktIncompatible;
019import java.util.concurrent.Callable;
020import org.checkerframework.checker.nullness.qual.Nullable;
021
022/**
023 * A listening executor service which forwards all its method calls to another listening executor
024 * service. Subclasses should override one or more methods to modify the behavior of the backing
025 * executor service 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 does <i>not</i> forward calls to {@code
029 * default} methods. Instead, it inherits their default implementations. When those implementations
030 * invoke methods, they invoke methods on the {@code ForwardingListeningExecutorService}.
031 *
032 * @author Isaac Shum
033 * @since 10.0
034 */
035@J2ktIncompatible
036@GwtIncompatible
037@ElementTypesAreNonnullByDefault
038public abstract class ForwardingListeningExecutorService extends ForwardingExecutorService
039    implements ListeningExecutorService {
040  /** Constructor for use by subclasses. */
041  protected ForwardingListeningExecutorService() {}
042
043  @Override
044  protected abstract ListeningExecutorService delegate();
045
046  @Override
047  public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) {
048    return delegate().submit(task);
049  }
050
051  @Override
052  public ListenableFuture<?> submit(Runnable task) {
053    return delegate().submit(task);
054  }
055
056  @Override
057  public <T extends @Nullable Object> ListenableFuture<T> submit(
058      Runnable task, @ParametricNullness T result) {
059    return delegate().submit(task, result);
060  }
061}