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