1/* 2 * Copyright (C) 2011 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package com.google.common.util.concurrent; 18 19import com.google.common.annotations.Beta; 20 21import java.util.concurrent.Future; 22 23/** 24 * Transforms a value, possibly asynchronously. For an example usage and more 25 * information, see {@link Futures#transform(ListenableFuture, AsyncFunction)}. 26 * 27 * @author Chris Povirk 28 * @since 11.0 29 */ 30@Beta 31public interface AsyncFunction<I, O> { 32 /** 33 * Returns an output {@code Future} to use in place of the given {@code 34 * input}. The output {@code Future} need not be {@linkplain Future#isDone 35 * done}, making {@code AsyncFunction} suitable for asynchronous derivations. 36 * 37 * <p>Throwing an exception from this method is equivalent to returning a 38 * failing {@code Future}. 39 */ 40 ListenableFuture<O> apply(I input) throws Exception; 41} 42