java.lang.AutoCloseable Maven / Gradle / Ivy
Show all versions of android-all Show documentation
/*
* Copyright (c) 2009, 2013, 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.lang;
/**
* An object that may hold resources (such as file or socket handles)
* until it is closed. The {@link #close()} method of an {@code AutoCloseable}
* object is called automatically when exiting a {@code
* try}-with-resources block for which the object has been declared in
* the resource specification header. This construction ensures prompt
* release, avoiding resource exhaustion exceptions and errors that
* may otherwise occur.
*
* @apiNote
* It is possible, and in fact common, for a base class to
* implement AutoCloseable even though not all of its subclasses or
* instances will hold releasable resources. For code that must operate
* in complete generality, or when it is known that the {@code AutoCloseable}
* instance requires resource release, it is recommended to use {@code
* try}-with-resources constructions. However, when using facilities such as
* {@link java.util.stream.Stream} that support both I/O-based and
* non-I/O-based forms, {@code try}-with-resources blocks are in
* general unnecessary when using non-I/O-based forms.
*
* @author Josh Bloch
* @since 1.7
*/
public interface AutoCloseable {
/**
* Closes this resource, relinquishing any underlying resources.
* This method is invoked automatically on objects managed by the
* {@code try}-with-resources statement.
*
*
While this interface method is declared to throw {@code
* Exception}, implementers are strongly encouraged to
* declare concrete implementations of the {@code close} method to
* throw more specific exceptions, or to throw no exception at all
* if the close operation cannot fail.
*
*
Cases where the close operation may fail require careful
* attention by implementers. It is strongly advised to relinquish
* the underlying resources and to internally mark the
* resource as closed, prior to throwing the exception. The {@code
* close} method is unlikely to be invoked more than once and so
* this ensures that the resources are released in a timely manner.
* Furthermore it reduces problems that could arise when the resource
* wraps, or is wrapped, by another resource.
*
*
Implementers of this interface are also strongly advised
* to not have the {@code close} method throw {@link
* InterruptedException}.
*
* This exception interacts with a thread's interrupted status,
* and runtime misbehavior is likely to occur if an {@code
* InterruptedException} is {@linkplain Throwable#addSuppressed
* suppressed}.
*
* More generally, if it would cause problems for an
* exception to be suppressed, the {@code AutoCloseable.close}
* method should not throw it.
*
*
Note that unlike the {@link java.io.Closeable#close close}
* method of {@link java.io.Closeable}, this {@code close} method
* is not required to be idempotent. In other words,
* calling this {@code close} method more than once may have some
* visible side effect, unlike {@code Closeable.close} which is
* required to have no effect if called more than once.
*
* However, implementers of this interface are strongly encouraged
* to make their {@code close} methods idempotent.
*
* @throws Exception if this resource cannot be closed
*/
void close() throws Exception;
}