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 * Copyright (c) 2009, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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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;
}