Callable.java revision 51b1b6997fd3f980076b8081f7f1165ccc2a4008 
1/*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.  Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25/*
26 * This file is available under and governed by the GNU General Public
27 * License version 2 only, as published by the Free Software Foundation.
28 * However, the following notice accompanied the original version of this
29 * file:
30 *
31 * Written by Doug Lea with assistance from members of JCP JSR-166
32 * Expert Group and released to the public domain, as explained at
33 * http://creativecommons.org/publicdomain/zero/1.0/
34 */
35
36package java.util.concurrent;
37
38/**
39 * A task that returns a result and may throw an exception.
40 * Implementors define a single method with no arguments called
41 * <tt>call</tt>.
42 *
43 * <p>The <tt>Callable</tt> interface is similar to {@link
44 * java.lang.Runnable}, in that both are designed for classes whose
45 * instances are potentially executed by another thread.  A
46 * <tt>Runnable</tt>, however, does not return a result and cannot
47 * throw a checked exception.
48 *
49 * <p> The {@link Executors} class contains utility methods to
50 * convert from other common forms to <tt>Callable</tt> classes.
51 *
52 * @see Executor
53 * @since 1.5
54 * @author Doug Lea
55 * @param <V> the result type of method <tt>call</tt>
56 */
57public interface Callable<V> {
58    /**
59     * Computes a result, or throws an exception if unable to do so.
60     *
61     * @return computed result
62     * @throws Exception if unable to compute a result
63     */
64    V call() throws Exception;
65}
66