/* * Copyright (c) 2007, 2009, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.nio.file; import java.io.IOException; /** * An object that may be registered with a watch service so that it can be * <em>watched</em> for changes and events. * * <p> This interface defines the {@link #register register} method to register * the object with a {@link WatchService} returning a {@link WatchKey} to * represent the registration. An object may be registered with more than one * watch service. Registration with a watch service is cancelled by invoking the * key's {@link WatchKey#cancel cancel} method. * * @since 1.7 * * @see Path#register */ public interface Watchable {     /**     * Registers an object with a watch service.     *     * <p> If the file system object identified by this object is currently     * registered with the watch service then the watch key, representing that     * registration, is returned after changing the event set or modifiers to     * those specified by the {@code events} and {@code modifiers} parameters.     * Changing the event set does not cause pending events for the object to be     * discarded. Objects are automatically registered for the {@link     * StandardWatchEventKinds#OVERFLOW OVERFLOW} event. This event is not     * required to be present in the array of events.     *     * <p> Otherwise the file system object has not yet been registered with the     * given watch service, so it is registered and the resulting new key is     * returned.     *     * <p> Implementations of this interface should specify the events they     * support.     *     * @param   watcher     *          the watch service to which this object is to be registered     * @param   events     *          the events for which this object should be registered     * @param   modifiers     *          the modifiers, if any, that modify how the object is registered     *     * @return  a key representing the registration of this object with the     *          given watch service     *     * @throws  UnsupportedOperationException     *          if unsupported events or modifiers are specified     * @throws  IllegalArgumentException     *          if an invalid of combination of events are modifiers are specified     * @throws  ClosedWatchServiceException     *          if the watch service is closed     * @throws  IOException     *          if an I/O error occurs     * @throws  SecurityException     *          if a security manager is installed and it denies an unspecified     *          permission required to monitor this object. Implementations of     *          this interface should specify the permission checks.     */    WatchKey register(WatchService watcher,                      WatchEvent.Kind<?>[] events,                      WatchEvent.Modifier... modifiers)        throws IOException;      /**     * Registers an object with a watch service.     *     * <p> An invocation of this method behaves in exactly the same way as the     * invocation     * <pre>     *     watchable.{@link #register(WatchService,WatchEvent.Kind[],WatchEvent.Modifier[]) register}(watcher, events, new WatchEvent.Modifier[0]);     * </pre>     *     * @param   watcher     *          the watch service to which this object is to be registered     * @param   events     *          the events for which this object should be registered     *     * @return  a key representing the registration of this object with the     *          given watch service     *     * @throws  UnsupportedOperationException     *          if unsupported events are specified     * @throws  IllegalArgumentException     *          if an invalid of combination of events are specified     * @throws  ClosedWatchServiceException     *          if the watch service is closed     * @throws  IOException     *          if an I/O error occurs     * @throws  SecurityException     *          if a security manager is installed and it denies an unspecified     *          permission required to monitor this object. Implementations of     *          this interface should specify the permission checks.     */    WatchKey register(WatchService watcher, WatchEvent.Kind<?>... events)        throws IOException;}