/*

 * Copyright 2007-2009 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.nio.file.attribute;

import java.util.concurrent.TimeUnit;

/**

 * Basic attributes associated with a file in a file system.

 *

 * <p> Basic file attributes are attributes that are common to many file systems

 * and consist of mandatory and optional file attributes as defined by this

 * interface.

 *

 * <p> <b>Usage Example:</b>

 * <pre>

 *    FileRef file = ...

 *    BasicFileAttributes attrs = Attributes.readBasicFileAttributes(file);

 * </pre>

 *

 * @since 1.7

 *

 * @see BasicFileAttributeView

 */

public interface BasicFileAttributes {

    /**

     * Returns the time of last modification.

     *

     * <p> The {@link #resolution() resolution} method returns the {@link TimeUnit}

     * to interpret the return value of this method.

     *

     * @return  A <code>long</code> value representing the time the file was

     *          last modified since the epoch (00:00:00 GMT, January 1, 1970),

     *          or {@code -1L} if the attribute is not supported.

     */

    long lastModifiedTime();

    /**

     * Returns the time of last access if supported.

     *

     * <p> The {@link #resolution() resolution} method returns the {@link TimeUnit}

     * to interpret the return value of this method.

     *

     * @return  A <code>long</code> value representing the time of last access

     *          since the epoch (00:00:00 GMT, January 1, 1970), or {@code -1L}

     *          if the attribute is not supported.

     */

    long lastAccessTime();

    /**

     * Returns the creation time if supported. The creation time is the time

     * that the file was created.

     *

     * <p> The {@link #resolution() resolution} method returns the {@link TimeUnit}

     * to interpret the return value of this method.

     *

     * @return  A <code>long</code> value representing the time the file was

     *          created since the epoch (00:00:00 GMT, January 1, 1970), or

     *          {@code -1L} if the attribute is not supported.

     */

    long creationTime();

    /**

     * Returns the {@link TimeUnit} required to interpret the time of last

     * modification, time of last access, and creation time.

     *

     * @return  The {@code TimeUnit} required to interpret the file time stamps

     */

    TimeUnit resolution();

    /**

     * Tells whether the file is a regular file with opaque content.

     */

    boolean isRegularFile();

    /**

     * Tells whether the file is a directory.

     */

    boolean isDirectory();

    /**

     * Tells whether the file is a symbolic-link.

     */

    boolean isSymbolicLink();

    /**

     * Tells whether the file is something other than a regular file, directory,

     * or link.

     */

    boolean isOther();

    /**

     * Returns the size of the file (in bytes). The size may differ from the

     * actual size on the file system due to compression, support for sparse

     * files, or other reasons. The size of files that are not {@link

     * #isRegularFile regular} files is implementation specific and

     * therefore unspecified.

     *

     * @return  The file size, in bytes

     */

    long size();

    /**

     * Returns the number of <em>links</em> to this file.

     *

     * <p> On file systems where the same file may be in several directories then

     * the link count is the number of directory entries for the file. The return

     * value is {@code 1} on file systems that only allow a file to have a

     * single name in a single directory.

     *

     * @see java.nio.file.Path#createLink

     */

    int linkCount();

    /**

     * Returns an object that uniquely identifies the given file, or {@code

     * null} if a file key is not available. On some platforms or file systems

     * it is possible to use an identifier, or a combination of identifiers to

     * uniquely identify a file. Such identifiers are important for operations

     * such as file tree traversal in file systems that support <a

     * href="../package-summary.html#links">symbolic links</a> or file systems

     * that allow a file to be an entry in more than one directory. On UNIX file

     * systems, for example, the <em>device ID</em> and <em>inode</em> are

     * commonly used for such purposes.

     *

     * <p> The file key returned by this method can only be guaranteed to be

     * unique if the file system and files remain static. Whether a file system

     * re-uses identifiers after a file is deleted is implementation dependent and

     * therefore unspecified.

     *

     * <p> File keys returned by this method can be compared for equality and are

     * suitable for use in collections. If the file system and files remain static,

     * and two files are the {@link java.nio.file.FileRef#isSameFile same} with

     * non-{@code null} file keys, then their file keys are equal.

     *

     * @see java.nio.file.Files#walkFileTree

     */

    Object fileKey();

}