    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
    017    package com.google.common.util.concurrent;
    018
    019    import com.google.common.annotations.Beta;
    020
    021    import java.util.concurrent.ExecutionException;
    022    import java.util.concurrent.Future;
    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     */
    033    @Beta
    034    public interface FutureCallback<V> {
    035      /**
    036       * Invoked with the result of the {@code Future} computation when it is
    037       * successful.
    038       */
    039      void onSuccess(V result);
    040
    041      /**
    042       * Invoked when a {@code Future} computation fails or is canceled.
    043       *
    044       * <p>If the future's {@link Future#get() get} method throws an {@link
    045       * ExecutionException}, then the cause is passed to this method. Any other
    046       * thrown object is passed unaltered.
    047       */
    048      void onFailure(Throwable t);
    049    }