001/*
002 * Copyright (C) 2011 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.util.concurrent;
018
019import java.util.concurrent.ExecutionException;
020import java.util.concurrent.Future;
021
022import javax.annotation.Nullable;
023
024/**
025 * A callback for accepting the results of a {@link java.util.concurrent.Future}
026 * computation asynchronously.
027 *
028 * <p>To attach to a {@link ListenableFuture} use {@link Futures#addCallback}.
029 *
030 * @author Anthony Zana
031 * @since 10.0
032 */
033public interface FutureCallback<V> {
034  /**
035   * Invoked with the result of the {@code Future} computation when it is
036   * successful.
037   */
038  void onSuccess(@Nullable V result);
039
040  /**
041   * Invoked when a {@code Future} computation fails or is canceled.
042   *
043   * <p>If the future's {@link Future#get() get} method throws an {@link
044   * ExecutionException}, then the cause is passed to this method. Any other
045   * thrown object is passed unaltered.
046   */
047  void onFailure(Throwable t);
048}