1 /* 2 * Copyright (c) 2009, 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.lang; 27 28 /** 29 * A resource that must be closed when it is no longer needed. 30 * 31 * @author Josh Bloch 32 * @since 1.7 33 */ 34 public interface AutoCloseable { 35 /** 36 * Closes this resource, relinquishing any underlying resources. 37 * This method is invoked automatically on objects managed by the 38 * {@code try}-with-resources statement. 39 * 40 * <p>While this interface method is declared to throw {@code 41 * Exception}, implementers are <em>strongly</em> encouraged to 42 * declare concrete implementations of the {@code close} method to 43 * throw more specific exceptions, or to throw no exception at all 44 * if the close operation cannot fail. 45 * 46 * <p> Cases where the close operation may fail require careful 47 * attention by implementers. It is strongly advised to relinquish 48 * the underlying resources and to internally <em>mark</em> the 49 * resource as closed, prior to throwing the exception. The {@code 50 * close} method is unlikely to be invoked more than once and so 51 * this ensures that the resources are released in a timely manner. 52 * Furthermore it reduces problems that could arise when the resource 53 * wraps, or is wrapped, by another resource. 54 * 55 * <p><em>Implementers of this interface are also strongly advised 56 * to not have the {@code close} method throw {@link 57 * InterruptedException}.</em> 58 * 59 * This exception interacts with a thread's interrupted status, 60 * and runtime misbehavior is likely to occur if an {@code 61 * InterruptedException} is {@linkplain Throwable#addSuppressed 62 * suppressed}. 63 * 64 * More generally, if it would cause problems for an 65 * exception to be suppressed, the {@code AutoCloseable.close} 66 * method should not throw it. 67 * 68 * <p>Note that unlike the {@link java.io.Closeable#close close} 69 * method of {@link java.io.Closeable}, this {@code close} method 70 * is <em>not</em> required to be idempotent. In other words, 71 * calling this {@code close} method more than once may have some 72 * visible side effect, unlike {@code Closeable.close} which is 73 * required to have no effect if called more than once. 74 * 75 * However, implementers of this interface are strongly encouraged 76 * to make their {@code close} methods idempotent. 77 * 78 * @throws Exception if this resource cannot be closed 79 */ 80 void close() throws Exception; 81 }