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 com.google.common.annotations.Beta; 020 021 import java.util.concurrent.Callable; 022 import java.util.concurrent.Executor; 023 import java.util.concurrent.FutureTask; 024 025 /** 026 * A {@link FutureTask} that also implements the {@link ListenableFuture} 027 * interface. Subclasses must make sure to call {@code super.done()} if they 028 * also override the {@link #done()} method, otherwise the listeners will not 029 * be called. 030 * 031 * @author Sven Mawson 032 * @since 1 033 */ 034 @Beta 035 public class ListenableFutureTask<V> extends FutureTask<V> 036 implements ListenableFuture<V> { 037 038 // The execution list to hold our listeners. 039 private final ExecutionList executionList = new ExecutionList(); 040 041 /** 042 * Creates a {@code ListenableFutureTask} that will upon running, execute the 043 * given {@code Callable}. 044 * 045 * @param callable the callable task 046 * @throws NullPointerException if callable is null 047 */ 048 public ListenableFutureTask(Callable<V> callable) { 049 super(callable); 050 } 051 052 /** 053 * Creates a {@code ListenableFutureTask} that will upon running, execute the 054 * given {@code Runnable}, and arrange that {@code get} will return the 055 * given result on successful completion. 056 * 057 * @param runnable the runnable task 058 * @param result the result to return on successful completion. If 059 * you don't need a particular result, consider using 060 * constructions of the form: 061 * {@code ListenableFuture<?> f = 062 * new ListenableFutureTask<Object>(runnable, null)} 063 * @throws NullPointerException if runnable is null 064 */ 065 public ListenableFutureTask(Runnable runnable, V result) { 066 super(runnable, result); 067 } 068 069 @Override 070 public void addListener(Runnable listener, Executor exec) { 071 executionList.add(listener, exec); 072 } 073 074 @Override 075 protected void done() { 076 executionList.run(); 077 } 078 }