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    }