1 /* 2 * Copyright (c) 2007, 2011, 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.nio.file; 27 28 import java.io.IOException; 29 30 /** 31 * An object that may be registered with a watch service so that it can be 32 * <em>watched</em> for changes and events. 33 * 34 * <p> This interface defines the {@link #register register} method to register 35 * the object with a {@link WatchService} returning a {@link WatchKey} to 36 * represent the registration. An object may be registered with more than one 37 * watch service. Registration with a watch service is cancelled by invoking the 38 * key's {@link WatchKey#cancel cancel} method. 39 * 40 * @since 1.7 41 * 42 * @see Path#register 43 */ 44 45 public interface Watchable { 46 47 /** 48 * Registers an object with a watch service. 49 * 50 * <p> If the file system object identified by this object is currently 51 * registered with the watch service then the watch key, representing that 52 * registration, is returned after changing the event set or modifiers to 53 * those specified by the {@code events} and {@code modifiers} parameters. 54 * Changing the event set does not cause pending events for the object to be 55 * discarded. Objects are automatically registered for the {@link 56 * StandardWatchEventKinds#OVERFLOW OVERFLOW} event. This event is not 57 * required to be present in the array of events. 58 * 59 * <p> Otherwise the file system object has not yet been registered with the 60 * given watch service, so it is registered and the resulting new key is 61 * returned. 62 * 63 * <p> Implementations of this interface should specify the events they 64 * support. 65 * 66 * @param watcher 67 * the watch service to which this object is to be registered 68 * @param events 69 * the events for which this object should be registered 70 * @param modifiers 71 * the modifiers, if any, that modify how the object is registered 72 * 73 * @return a key representing the registration of this object with the 74 * given watch service 75 * 76 * @throws UnsupportedOperationException 77 * if unsupported events or modifiers are specified 78 * @throws IllegalArgumentException 79 * if an invalid of combination of events are modifiers are specified 80 * @throws ClosedWatchServiceException 81 * if the watch service is closed 82 * @throws IOException 83 * if an I/O error occurs 84 * @throws SecurityException 85 * if a security manager is installed and it denies an unspecified 86 * permission required to monitor this object. Implementations of 87 * this interface should specify the permission checks. 88 */ register(WatchService watcher, WatchEvent.Kind<?>[] events, WatchEvent.Modifier... modifiers)89 WatchKey register(WatchService watcher, 90 WatchEvent.Kind<?>[] events, 91 WatchEvent.Modifier... modifiers) 92 throws IOException; 93 94 95 /** 96 * Registers an object with a watch service. 97 * 98 * <p> An invocation of this method behaves in exactly the same way as the 99 * invocation 100 * <pre> 101 * watchable.{@link #register(WatchService,WatchEvent.Kind[],WatchEvent.Modifier[]) register}(watcher, events, new WatchEvent.Modifier[0]); 102 * </pre> 103 * 104 * @param watcher 105 * the watch service to which this object is to be registered 106 * @param events 107 * the events for which this object should be registered 108 * 109 * @return a key representing the registration of this object with the 110 * given watch service 111 * 112 * @throws UnsupportedOperationException 113 * if unsupported events are specified 114 * @throws IllegalArgumentException 115 * if an invalid of combination of events are specified 116 * @throws ClosedWatchServiceException 117 * if the watch service is closed 118 * @throws IOException 119 * if an I/O error occurs 120 * @throws SecurityException 121 * if a security manager is installed and it denies an unspecified 122 * permission required to monitor this object. Implementations of 123 * this interface should specify the permission checks. 124 */ register(WatchService watcher, WatchEvent.Kind<?>... events)125 WatchKey register(WatchService watcher, WatchEvent.Kind<?>... events) 126 throws IOException; 127 } 128