001    /*
002     * Copyright (C) 2009 Google Inc.
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.Executor;
022    
023    /**
024     * A {@link ForwardingFuture} that also implements {@link ListenableFuture}.
025     * Subclasses will have to provide a delegate {@link ListenableFuture} through
026     * the {@link #delegate()} method.
027     *
028     * @param <V> The result type returned by this Future's <tt>get</tt> method
029     *
030     * @author Shardul Deo
031     * @since 4
032     */
033    @Beta
034    public abstract class ForwardingListenableFuture<V> extends ForwardingFuture<V>
035        implements ListenableFuture<V> {
036    
037      /** Constructor for use by subclasses. */
038      protected ForwardingListenableFuture() {}
039    
040      @Override
041      protected abstract ListenableFuture<V> delegate();
042    
043      @Override
044      public void addListener(Runnable listener, Executor exec) {
045        delegate().addListener(listener, exec);
046      }
047    }