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 22 * questions. 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 36 package 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 * {@code call}. 42 * 43 * <p>The {@code Callable} 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 * {@code Runnable}, 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 {@code Callable} classes. 51 * 52 * @see Executor 53 * @since 1.5 54 * @author Doug Lea 55 * @param <V> the result type of method {@code call} 56 */ 57 @FunctionalInterface 58 public interface Callable<V> { 59 /** 60 * Computes a result, or throws an exception if unable to do so. 61 * 62 * @return computed result 63 * @throws Exception if unable to compute a result 64 */ call()65 V call() throws Exception; 66 } 67