1 /* 2 * Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang; 27 28 /** 29 * The {@code Runnable} interface should be implemented by any 30 * class whose instances are intended to be executed by a thread. The 31 * class must define a method of no arguments called {@code run}. 32 * <p> 33 * This interface is designed to provide a common protocol for objects that 34 * wish to execute code while they are active. For example, 35 * {@code Runnable} is implemented by class {@code Thread}. 36 * Being active simply means that a thread has been started and has not 37 * yet been stopped. 38 * <p> 39 * In addition, {@code Runnable} provides the means for a class to be 40 * active while not subclassing {@code Thread}. A class that implements 41 * {@code Runnable} can run without subclassing {@code Thread} 42 * by instantiating a {@code Thread} instance and passing itself in 43 * as the target. In most cases, the {@code Runnable} interface should 44 * be used if you are only planning to override the {@code run()} 45 * method and no other {@code Thread} methods. 46 * This is important because classes should not be subclassed 47 * unless the programmer intends on modifying or enhancing the fundamental 48 * behavior of the class. 49 * 50 * @author Arthur van Hoff 51 * @see java.lang.Thread 52 * @see java.util.concurrent.Callable 53 * @since 1.0 54 */ 55 @FunctionalInterface 56 public interface Runnable { 57 /** 58 * When an object implementing interface {@code Runnable} is used 59 * to create a thread, starting the thread causes the object's 60 * {@code run} method to be called in that separately executing 61 * thread. 62 * <p> 63 * The general contract of the method {@code run} is that it may 64 * take any action whatsoever. 65 * 66 * @see java.lang.Thread#run() 67 */ run()68 public abstract void run(); 69 } 70