001 /* 002 * Copyright (C) 2008 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 java.util.concurrent.Callable; 020 import java.util.concurrent.Executor; 021 import java.util.concurrent.FutureTask; 022 023 import javax.annotation.Nullable; 024 025 /** 026 * A {@link FutureTask} that also implements the {@link ListenableFuture} 027 * interface. Unlike {@code FutureTask}, {@code ListenableFutureTask} does not 028 * provide an overrideable {@link FutureTask#done() done()} method. For similar 029 * functionality, call {@link #addListener}. 030 * 031 * <p> 032 * 033 * @author Sven Mawson 034 * @since 1.0 035 */ 036 public final class ListenableFutureTask<V> extends FutureTask<V> 037 implements ListenableFuture<V> { 038 039 // The execution list to hold our listeners. 040 private final ExecutionList executionList = new ExecutionList(); 041 042 /** 043 * Creates a {@code ListenableFutureTask} that will upon running, execute the 044 * given {@code Callable}. 045 * 046 * @param callable the callable task 047 * @since 10.0 048 */ 049 public static <V> ListenableFutureTask<V> create(Callable<V> callable) { 050 return new ListenableFutureTask<V>(callable); 051 } 052 053 /** 054 * Creates a {@code ListenableFutureTask} that will upon running, execute the 055 * given {@code Runnable}, and arrange that {@code get} will return the 056 * given result on successful completion. 057 * 058 * @param runnable the runnable task 059 * @param result the result to return on successful completion. If you don't 060 * need a particular result, consider using constructions of the form: 061 * {@code ListenableFuture<?> f = ListenableFutureTask.create(runnable, 062 * null)} 063 * @since 10.0 064 */ 065 public static <V> ListenableFutureTask<V> create( 066 Runnable runnable, @Nullable V result) { 067 return new ListenableFutureTask<V>(runnable, result); 068 } 069 070 private ListenableFutureTask(Callable<V> callable) { 071 super(callable); 072 } 073 074 private ListenableFutureTask(Runnable runnable, @Nullable V result) { 075 super(runnable, result); 076 } 077 078 @Override 079 public void addListener(Runnable listener, Executor exec) { 080 executionList.add(listener, exec); 081 } 082 083 /** 084 * Internal implementation detail used to invoke the listeners. 085 */ 086 @Override 087 protected void done() { 088 executionList.execute(); 089 } 090 }