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 * 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

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 */

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

 * <p>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.

     *

     * <p>While this interface method is declared to throw {@code

     * Exception}, implementers are <em>strongly</em> 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.

     *

     * <p> Cases where the close operation may fail require careful

     * attention by implementers. It is strongly advised to relinquish

     * the underlying resources and to internally <em>mark</em> 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.

     *

     * <p><em>Implementers of this interface are also strongly advised

     * to not have the {@code close} method throw {@link

     * InterruptedException}.</em>

     *

     * 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.

     *

     * <p>Note that unlike the {@link java.io.Closeable#close close}

     * method of {@link java.io.Closeable}, this {@code close} method

     * is <em>not</em> 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;

}