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   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   * This code is free software; you can redistribute it and/or modify it
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   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
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   *
   * 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
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   * You should have received a copy of the GNU General Public License version
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   * 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.nio.file;
  
  import java.io.File;
  import java.io.IOException;
  import java.net.URI;
  import java.util.Iterator;
  
  /**
   * An object that may be used to locate a file in a file system. It will
   * typically represent a system dependent file path.
   *
   * <p> A {@code Path} represents a path that is hierarchical and composed of a
   * sequence of directory and file name elements separated by a special separator
   * or delimiter. A <em>root component</em>, that identifies a file system
   * hierarchy, may also be present. The name element that is <em>farthest</em>
   * from the root of the directory hierarchy is the name of a file or directory.
   * The other name elements are directory names. A {@code Path} can represent a
   * root, a root and a sequence of names, or simply one or more name elements.
   * A {@code Path} is considered to be an <i>empty path</i> if it consists
   * solely of one name element that is empty. Accessing a file using an
   * <i>empty path</i> is equivalent to accessing the default directory of the
   * file system. {@code Path} defines the {@link #getFileName() getFileName},
   * {@link #getParent getParent}, {@link #getRoot getRoot}, and {@link #subpath
   * subpath} methods to access the path components or a subsequence of its name
   * elements.
   *
   * <p> In addition to accessing the components of a path, a {@code Path} also
   * defines the {@link #resolve(Path) resolve} and {@link #resolveSibling(Path)
   * resolveSibling} methods to combine paths. The {@link #relativize relativize}
   * method that can be used to construct a relative path between two paths.
   * Paths can be {@link #compareTo compared}, and tested against each other using
   * the {@link #startsWith startsWith} and {@link #endsWith endsWith} methods.
   *
   * <p> This interface extends {@link Watchable} interface so that a directory
   * located by a path can be {@link #register registered} with a {@link
   * WatchService} and entries in the directory watched. </p>
   *
   * <p> <b>WARNING:</b> This interface is only intended to be implemented by
   * those developing custom file system implementations. Methods may be added to
   * this interface in future releases. </p>
   *
   * <h2>Accessing Files</h2>
   * <p> Paths may be used with the {@link Files} class to operate on files,
   * directories, and other types of files. For example, suppose we want a {@link
   * java.io.BufferedReader} to read text from a file "{@code access.log}". The
   * file is located in a directory "{@code logs}" relative to the current working
   * directory and is UTF-8 encoded.
   * <pre>
   *     Path path = FileSystems.getDefault().getPath("logs", "access.log");
   *     BufferedReader reader = Files.newBufferedReader(path, StandardCharsets.UTF_8);
   * </pre>
   *
   * <a name="interop"></a><h2>Interoperability</h2>
   * <p> Paths associated with the default {@link
   * java.nio.file.spi.FileSystemProvider provider} are generally interoperable
   * with the {@link File java.io.File} class. Paths created by other
   * providers are unlikely to be interoperable with the abstract path names
   * represented by {@code java.io.File}. The {@link File#toPath toPath}
   * method may be used to obtain a {@code Path} from the abstract path name
   * represented by a {@code java.io.File} object. The resulting {@code Path} can
   * be used to operate on the same file as the {@code java.io.File} object. In
   * addition, the {@link #toFile toFile} method is useful to construct a {@code
   * File} from the {@code String} representation of a {@code Path}.
   *
   * <h2>Concurrency</h2>
   * <p> Implementations of this interface are immutable and safe for use by
   * multiple concurrent threads.
   *
   * @since 1.7
   * @see Paths
   */
  
  public interface Path
      extends Comparable<Path>, Iterable<Path>, Watchable
  {
      /**
       * Returns the file system that created this object.
       *
       * @return  the file system that created this object
       */
      FileSystem getFileSystem();
  
      /**
       * Tells whether or not this path is absolute.
       *
       * <p> An absolute path is complete in that it doesn't need to be combined
       * with other path information in order to locate a file.
       *
       * @return  {@code true} if, and only if, this path is absolute
       */
      boolean isAbsolute();
  
      /**
       * Returns the root component of this path as a {@code Path} object,
       * or {@code null} if this path does not have a root component.
       *
       * @return  a path representing the root component of this path,
       *          or {@code null}
       */
      Path getRoot();
  
      /**
       * Returns the name of the file or directory denoted by this path as a
       * {@code Path} object. The file name is the <em>farthest</em> element from
       * the root in the directory hierarchy.
       *
       * @return  a path representing the name of the file or directory, or
       *          {@code null} if this path has zero elements
       */
      Path getFileName();
  
      /**
       * Returns the <em>parent path</em>, or {@code null} if this path does not
       * have a parent.
       *
       * <p> The parent of this path object consists of this path's root
       * component, if any, and each element in the path except for the
       * <em>farthest</em> from the root in the directory hierarchy. This method
       * does not access the file system; the path or its parent may not exist.
       * Furthermore, this method does not eliminate special names such as "."
       * and ".." that may be used in some implementations. On UNIX for example,
       * the parent of "{@code /a/b/c}" is "{@code /a/b}", and the parent of
       * {@code "x/y/.}" is "{@code x/y}". This method may be used with the {@link
       * #normalize normalize} method, to eliminate redundant names, for cases where
       * <em>shell-like</em> navigation is required.
       *
       * <p> If this path has one or more elements, and no root component, then
       * this method is equivalent to evaluating the expression:
       * <blockquote><pre>
       * subpath(0,&nbsp;getNameCount()-1);
       * </pre></blockquote>
       *
       * @return  a path representing the path's parent
       */
      Path getParent();
  
      /**
       * Returns the number of name elements in the path.
       *
       * @return  the number of elements in the path, or {@code 0} if this path
       *          only represents a root component
       */
      int getNameCount();
  
      /**
       * Returns a name element of this path as a {@code Path} object.
       *
       * <p> The {@code index} parameter is the index of the name element to return.
       * The element that is <em>closest</em> to the root in the directory hierarchy
       * has index {@code 0}. The element that is <em>farthest</em> from the root
       * has index {@link #getNameCount count}{@code -1}.
       *
       * @param   index
       *          the index of the element
       *
       * @return  the name element
       *
       * @throws  IllegalArgumentException
       *          if {@code index} is negative, {@code index} is greater than or
       *          equal to the number of elements, or this path has zero name
       *          elements
       */
      Path getName(int index);
  
      /**
       * Returns a relative {@code Path} that is a subsequence of the name
       * elements of this path.
       *
       * <p> The {@code beginIndex} and {@code endIndex} parameters specify the
       * subsequence of name elements. The name that is <em>closest</em> to the root
       * in the directory hierarchy has index {@code 0}. The name that is
       * <em>farthest</em> from the root has index {@link #getNameCount
       * count}{@code -1}. The returned {@code Path} object has the name elements
       * that begin at {@code beginIndex} and extend to the element at index {@code
       * endIndex-1}.
       *
       * @param   beginIndex
       *          the index of the first element, inclusive
       * @param   endIndex
       *          the index of the last element, exclusive
       *
       * @return  a new {@code Path} object that is a subsequence of the name
       *          elements in this {@code Path}
       *
       * @throws  IllegalArgumentException
       *          if {@code beginIndex} is negative, or greater than or equal to
       *          the number of elements. If {@code endIndex} is less than or
       *          equal to {@code beginIndex}, or larger than the number of elements.
       */
      Path subpath(int beginIndex, int endIndex);
  
      /**
       * Tests if this path starts with the given path.
       *
       * <p> This path <em>starts</em> with the given path if this path's root
       * component <em>starts</em> with the root component of the given path,
       * and this path starts with the same name elements as the given path.
       * If the given path has more name elements than this path then {@code false}
       * is returned.
       *
       * <p> Whether or not the root component of this path starts with the root
       * component of the given path is file system specific. If this path does
       * not have a root component and the given path has a root component then
       * this path does not start with the given path.
       *
       * <p> If the given path is associated with a different {@code FileSystem}
       * to this path then {@code false} is returned.
       *
       * @param   other
       *          the given path
       *
       * @return  {@code true} if this path starts with the given path; otherwise
       *          {@code false}
       */
      boolean startsWith(Path other);
  
      /**
       * Tests if this path starts with a {@code Path}, constructed by converting
       * the given path string, in exactly the manner specified by the {@link
       * #startsWith(Path) startsWith(Path)} method. On UNIX for example, the path
       * "{@code foo/bar}" starts with "{@code foo}" and "{@code foo/bar}". It
       * does not start with "{@code f}" or "{@code fo}".
       *
       * @param   other
       *          the given path string
       *
       * @return  {@code true} if this path starts with the given path; otherwise
       *          {@code false}
       *
       * @throws  InvalidPathException
       *          If the path string cannot be converted to a Path.
       */
      boolean startsWith(String other);
  
      /**
       * Tests if this path ends with the given path.
       *
       * <p> If the given path has <em>N</em> elements, and no root component,
       * and this path has <em>N</em> or more elements, then this path ends with
       * the given path if the last <em>N</em> elements of each path, starting at
       * the element farthest from the root, are equal.
       *
       * <p> If the given path has a root component then this path ends with the
       * given path if the root component of this path <em>ends with</em> the root
       * component of the given path, and the corresponding elements of both paths
       * are equal. Whether or not the root component of this path ends with the
       * root component of the given path is file system specific. If this path
       * does not have a root component and the given path has a root component
       * then this path does not end with the given path.
       *
       * <p> If the given path is associated with a different {@code FileSystem}
       * to this path then {@code false} is returned.
       *
       * @param   other
       *          the given path
       *
       * @return  {@code true} if this path ends with the given path; otherwise
       *          {@code false}
       */
      boolean endsWith(Path other);
  
      /**
       * Tests if this path ends with a {@code Path}, constructed by converting
       * the given path string, in exactly the manner specified by the {@link
       * #endsWith(Path) endsWith(Path)} method. On UNIX for example, the path
       * "{@code foo/bar}" ends with "{@code foo/bar}" and "{@code bar}". It does
       * not end with "{@code r}" or "{@code /bar}". Note that trailing separators
       * are not taken into account, and so invoking this method on the {@code
       * Path}"{@code foo/bar}" with the {@code String} "{@code bar/}" returns
       * {@code true}.
       *
       * @param   other
       *          the given path string
       *
       * @return  {@code true} if this path ends with the given path; otherwise
       *          {@code false}
       *
       * @throws  InvalidPathException
       *          If the path string cannot be converted to a Path.
       */
      boolean endsWith(String other);
  
      /**
       * Returns a path that is this path with redundant name elements eliminated.
       *
       * <p> The precise definition of this method is implementation dependent but
       * in general it derives from this path, a path that does not contain
       * <em>redundant</em> name elements. In many file systems, the "{@code .}"
       * and "{@code ..}" are special names used to indicate the current directory
       * and parent directory. In such file systems all occurrences of "{@code .}"
       * are considered redundant. If a "{@code ..}" is preceded by a
       * non-"{@code ..}" name then both names are considered redundant (the
       * process to identify such names is repeated until it is no longer
       * applicable).
       *
       * <p> This method does not access the file system; the path may not locate
       * a file that exists. Eliminating "{@code ..}" and a preceding name from a
       * path may result in the path that locates a different file than the original
       * path. This can arise when the preceding name is a symbolic link.
       *
       * @return  the resulting path or this path if it does not contain
       *          redundant name elements; an empty path is returned if this path
       *          does have a root component and all name elements are redundant
       *
       * @see #getParent
       * @see #toRealPath
       */
      Path normalize();
  
      // -- resolution and relativization --
  
      /**
       * Resolve the given path against this path.
       *
       * <p> If the {@code other} parameter is an {@link #isAbsolute() absolute}
       * path then this method trivially returns {@code other}. If {@code other}
       * is an <i>empty path</i> then this method trivially returns this path.
       * Otherwise this method considers this path to be a directory and resolves
       * the given path against this path. In the simplest case, the given path
       * does not have a {@link #getRoot root} component, in which case this method
       * <em>joins</em> the given path to this path and returns a resulting path
       * that {@link #endsWith ends} with the given path. Where the given path has
       * a root component then resolution is highly implementation dependent and
       * therefore unspecified.
       *
       * @param   other
       *          the path to resolve against this path
       *
       * @return  the resulting path
       *
       * @see #relativize
       */
      Path resolve(Path other);
  
      /**
       * Converts a given path string to a {@code Path} and resolves it against
       * this {@code Path} in exactly the manner specified by the {@link
       * #resolve(Path) resolve} method. For example, suppose that the name
       * separator is "{@code /}" and a path represents "{@code foo/bar}", then
       * invoking this method with the path string "{@code gus}" will result in
       * the {@code Path} "{@code foo/bar/gus}".
       *
       * @param   other
       *          the path string to resolve against this path
       *
       * @return  the resulting path
       *
       * @throws  InvalidPathException
       *          if the path string cannot be converted to a Path.
       *
       * @see FileSystem#getPath
       */
      Path resolve(String other);
  
      /**
       * Resolves the given path against this path's {@link #getParent parent}
       * path. This is useful where a file name needs to be <i>replaced</i> with
       * another file name. For example, suppose that the name separator is
       * "{@code /}" and a path represents "{@code dir1/dir2/foo}", then invoking
       * this method with the {@code Path} "{@code bar}" will result in the {@code
       * Path} "{@code dir1/dir2/bar}". If this path does not have a parent path,
       * or {@code other} is {@link #isAbsolute() absolute}, then this method
       * returns {@code other}. If {@code other} is an empty path then this method
       * returns this path's parent, or where this path doesn't have a parent, the
       * empty path.
       *
       * @param   other
       *          the path to resolve against this path's parent
       *
       * @return  the resulting path
       *
       * @see #resolve(Path)
       */
      Path resolveSibling(Path other);
  
      /**
       * Converts a given path string to a {@code Path} and resolves it against
       * this path's {@link #getParent parent} path in exactly the manner
       * specified by the {@link #resolveSibling(Path) resolveSibling} method.
       *
       * @param   other
       *          the path string to resolve against this path's parent
       *
       * @return  the resulting path
       *
       * @throws  InvalidPathException
       *          if the path string cannot be converted to a Path.
       *
       * @see FileSystem#getPath
       */
      Path resolveSibling(String other);
  
      /**
       * Constructs a relative path between this path and a given path.
       *
       * <p> Relativization is the inverse of {@link #resolve(Path) resolution}.
       * This method attempts to construct a {@link #isAbsolute relative} path
       * that when {@link #resolve(Path) resolved} against this path, yields a
       * path that locates the same file as the given path. For example, on UNIX,
       * if this path is {@code "/a/b"} and the given path is {@code "/a/b/c/d"}
       * then the resulting relative path would be {@code "c/d"}. Where this
       * path and the given path do not have a {@link #getRoot root} component,
       * then a relative path can be constructed. A relative path cannot be
       * constructed if only one of the paths have a root component. Where both
       * paths have a root component then it is implementation dependent if a
       * relative path can be constructed. If this path and the given path are
       * {@link #equals equal} then an <i>empty path</i> is returned.
       *
       * <p> For any two {@link #normalize normalized} paths <i>p</i> and
       * <i>q</i>, where <i>q</i> does not have a root component,
       * <blockquote>
       *   <i>p</i><tt>.relativize(</tt><i>p</i><tt>.resolve(</tt><i>q</i><tt>)).equals(</tt><i>q</i><tt>)</tt>
       * </blockquote>
       *
       * <p> When symbolic links are supported, then whether the resulting path,
       * when resolved against this path, yields a path that can be used to locate
       * the {@link Files#isSameFile same} file as {@code other} is implementation
       * dependent. For example, if this path is  {@code "/a/b"} and the given
       * path is {@code "/a/x"} then the resulting relative path may be {@code
       * "../x"}. If {@code "b"} is a symbolic link then is implementation
       * dependent if {@code "a/b/../x"} would locate the same file as {@code "/a/x"}.
       *
       * @param   other
       *          the path to relativize against this path
       *
       * @return  the resulting relative path, or an empty path if both paths are
       *          equal
       *
       * @throws  IllegalArgumentException
       *          if {@code other} is not a {@code Path} that can be relativized
       *          against this path
       */
      Path relativize(Path other);
  
      /**
       * Returns a URI to represent this path.
       *
       * <p> This method constructs an absolute {@link URI} with a {@link
       * URI#getScheme() scheme} equal to the URI scheme that identifies the
       * provider. The exact form of the scheme specific part is highly provider
       * dependent.
       *
       * <p> In the case of the default provider, the URI is hierarchical with
       * a {@link URI#getPath() path} component that is absolute. The query and
       * fragment components are undefined. Whether the authority component is
       * defined or not is implementation dependent. There is no guarantee that
       * the {@code URI} may be used to construct a {@link File java.io.File}.
       * In particular, if this path represents a Universal Naming Convention (UNC)
       * path, then the UNC server name may be encoded in the authority component
       * of the resulting URI. In the case of the default provider, and the file
       * exists, and it can be determined that the file is a directory, then the
       * resulting {@code URI} will end with a slash.
       *
       * <p> The default provider provides a similar <em>round-trip</em> guarantee
       * to the {@link File} class. For a given {@code Path} <i>p</i> it
       * is guaranteed that
       * <blockquote><tt>
       * {@link Paths#get(URI) Paths.get}(</tt><i>p</i><tt>.toUri()).equals(</tt><i>p</i>
       * <tt>.{@link #toAbsolutePath() toAbsolutePath}())</tt>
       * </blockquote>
       * so long as the original {@code Path}, the {@code URI}, and the new {@code
       * Path} are all created in (possibly different invocations of) the same
       * Java virtual machine. Whether other providers make any guarantees is
       * provider specific and therefore unspecified.
       *
       * <p> When a file system is constructed to access the contents of a file
       * as a file system then it is highly implementation specific if the returned
       * URI represents the given path in the file system or it represents a
       * <em>compound</em> URI that encodes the URI of the enclosing file system.
       * A format for compound URIs is not defined in this release; such a scheme
       * may be added in a future release.
       *
       * @return  the URI representing this path
       *
       * @throws  java.io.IOError
       *          if an I/O error occurs obtaining the absolute path, or where a
       *          file system is constructed to access the contents of a file as
       *          a file system, and the URI of the enclosing file system cannot be
       *          obtained
       *
       * @throws  SecurityException
       *          In the case of the default provider, and a security manager
       *          is installed, the {@link #toAbsolutePath toAbsolutePath} method
       *          throws a security exception.
       */
      URI toUri();
  
      /**
       * Returns a {@code Path} object representing the absolute path of this
       * path.
       *
       * <p> If this path is already {@link Path#isAbsolute absolute} then this
       * method simply returns this path. Otherwise, this method resolves the path
       * in an implementation dependent manner, typically by resolving the path
       * against a file system default directory. Depending on the implementation,
       * this method may throw an I/O error if the file system is not accessible.
       *
       * @return  a {@code Path} object representing the absolute path
       *
       * @throws  java.io.IOError
       *          if an I/O error occurs
       * @throws  SecurityException
       *          In the case of the default provider, a security manager
       *          is installed, and this path is not absolute, then the security
       *          manager's {@link SecurityManager#checkPropertyAccess(String)
       *          checkPropertyAccess} method is invoked to check access to the
       *          system property {@code user.dir}
       */
      Path toAbsolutePath();
  
      /**
       * Returns the <em>real</em> path of an existing file.
       *
       * <p> The precise definition of this method is implementation dependent but
       * in general it derives from this path, an {@link #isAbsolute absolute}
       * path that locates the {@link Files#isSameFile same} file as this path, but
       * with name elements that represent the actual name of the directories
       * and the file. For example, where filename comparisons on a file system
       * are case insensitive then the name elements represent the names in their
       * actual case. Additionally, the resulting path has redundant name
       * elements removed.
       *
       * <p> If this path is relative then its absolute path is first obtained,
       * as if by invoking the {@link #toAbsolutePath toAbsolutePath} method.
       *
       * <p> The {@code options} array may be used to indicate how symbolic links
       * are handled. By default, symbolic links are resolved to their final
       * target. If the option {@link LinkOption#NOFOLLOW_LINKS NOFOLLOW_LINKS} is
       * present then this method does not resolve symbolic links.
       *
       * Some implementations allow special names such as "{@code ..}" to refer to
       * the parent directory. When deriving the <em>real path</em>, and a
       * "{@code ..}" (or equivalent) is preceded by a non-"{@code ..}" name then
       * an implementation will typically cause both names to be removed. When
       * not resolving symbolic links and the preceding name is a symbolic link
       * then the names are only removed if it guaranteed that the resulting path
       * will locate the same file as this path.
       *
       * @param   options
       *          options indicating how symbolic links are handled
       *
       * @return  an absolute path represent the <em>real</em> path of the file
       *          located by this object
       *
       * @throws  IOException
       *          if the file does not exist or an I/O error occurs
       * @throws  SecurityException
       *          In the case of the default provider, and a security manager
       *          is installed, its {@link SecurityManager#checkRead(String) checkRead}
       *          method is invoked to check read access to the file, and where
       *          this path is not absolute, its {@link SecurityManager#checkPropertyAccess(String)
       *          checkPropertyAccess} method is invoked to check access to the
       *          system property {@code user.dir}
       */
      Path toRealPath(LinkOption... options) throws IOException;
  
      /**
       * Returns a {@link File} object representing this path. Where this {@code
       * Path} is associated with the default provider, then this method is
       * equivalent to returning a {@code File} object constructed with the
       * {@code String} representation of this path.
       *
       * <p> If this path was created by invoking the {@code File} {@link
       * File#toPath toPath} method then there is no guarantee that the {@code
       * File} object returned by this method is {@link #equals equal} to the
       * original {@code File}.
       *
       * @return  a {@code File} object representing this path
       *
       * @throws  UnsupportedOperationException
       *          if this {@code Path} is not associated with the default provider
       */
      File toFile();
  
      // -- watchable --
  
      /**
       * Registers the file located by this path with a watch service.
       *
       * <p> In this release, this path locates a directory that exists. The
       * directory is registered with the watch service so that entries in the
       * directory can be watched. The {@code events} parameter is the events to
       * register and may contain the following events:
       * <ul>
       *   <li>{@link StandardWatchEventKinds#ENTRY_CREATE ENTRY_CREATE} -
       *       entry created or moved into the directory</li>
       *   <li>{@link StandardWatchEventKinds#ENTRY_DELETE ENTRY_DELETE} -
       *        entry deleted or moved out of the directory</li>
       *   <li>{@link StandardWatchEventKinds#ENTRY_MODIFY ENTRY_MODIFY} -
       *        entry in directory was modified</li>
       * </ul>
       *
       * <p> The {@link WatchEvent#context context} for these events is the
       * relative path between the directory located by this path, and the path
       * that locates the directory entry that is created, deleted, or modified.
       *
       * <p> The set of events may include additional implementation specific
       * event that are not defined by the enum {@link StandardWatchEventKinds}
       *
       * <p> The {@code modifiers} parameter specifies <em>modifiers</em> that
       * qualify how the directory is registered. This release does not define any
       * <em>standard</em> modifiers. It may contain implementation specific
       * modifiers.
       *
       * <p> Where a file is registered with a watch service by means of a symbolic
       * link then it is implementation specific if the watch continues to depend
       * on the existence of the symbolic link after it is registered.
       *
       * @param   watcher
       *          the watch service to which this object is to be registered
       * @param   events
       *          the events for which this object should be registered
       * @param   modifiers
       *          the modifiers, if any, that modify how the object is registered
       *
       * @return  a key representing the registration of this object with the
       *          given watch service
       *
       * @throws  UnsupportedOperationException
       *          if unsupported events or modifiers are specified
       * @throws  IllegalArgumentException
       *          if an invalid combination of events or modifiers is specified
       * @throws  ClosedWatchServiceException
       *          if the watch service is closed
       * @throws  NotDirectoryException
       *          if the file is registered to watch the entries in a directory
       *          and the file is not a directory  <i>(optional specific exception)</i>
       * @throws  IOException
       *          if an I/O error occurs
       * @throws  SecurityException
       *          In the case of the default provider, and a security manager is
       *          installed, the {@link SecurityManager#checkRead(String) checkRead}
       *          method is invoked to check read access to the file.
       */
      @Override
      WatchKey register(WatchService watcher,
                        WatchEvent.Kind<?>[] events,
                        WatchEvent.Modifier... modifiers)
          throws IOException;
  
      /**
       * Registers the file located by this path with a watch service.
       *
       * <p> An invocation of this method behaves in exactly the same way as the
       * invocation
       * <pre>
       *     watchable.{@link #register(WatchService,WatchEvent.Kind[],WatchEvent.Modifier[]) register}(watcher, events, new WatchEvent.Modifier[0]);
       * </pre>
       *
       * <p> <b>Usage Example:</b>
       * Suppose we wish to register a directory for entry create, delete, and modify
       * events:
       * <pre>
       *     Path dir = ...
       *     WatchService watcher = ...
       *
       *     WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
       * </pre>
       * @param   watcher
       *          The watch service to which this object is to be registered
       * @param   events
       *          The events for which this object should be registered
       *
       * @return  A key representing the registration of this object with the
       *          given watch service
       *
       * @throws  UnsupportedOperationException
       *          If unsupported events are specified
       * @throws  IllegalArgumentException
       *          If an invalid combination of events is specified
       * @throws  ClosedWatchServiceException
       *          If the watch service is closed
       * @throws  NotDirectoryException
       *          If the file is registered to watch the entries in a directory
       *          and the file is not a directory  <i>(optional specific exception)</i>
       * @throws  IOException
       *          If an I/O error occurs
       * @throws  SecurityException
       *          In the case of the default provider, and a security manager is
       *          installed, the {@link SecurityManager#checkRead(String) checkRead}
       *          method is invoked to check read access to the file.
       */
      @Override
      WatchKey register(WatchService watcher,
                        WatchEvent.Kind<?>... events)
          throws IOException;
  
      // -- Iterable --
  
      /**
       * Returns an iterator over the name elements of this path.
       *
       * <p> The first element returned by the iterator represents the name
       * element that is closest to the root in the directory hierarchy, the
       * second element is the next closest, and so on. The last element returned
       * is the name of the file or directory denoted by this path. The {@link
       * #getRoot root} component, if present, is not returned by the iterator.
       *
       * @return  an iterator over the name elements of this path.
       */
      @Override
      Iterator<Path> iterator();
  
      // -- compareTo/equals/hashCode --
  
      /**
       * Compares two abstract paths lexicographically. The ordering defined by
       * this method is provider specific, and in the case of the default
       * provider, platform specific. This method does not access the file system
       * and neither file is required to exist.
       *
       * <p> This method may not be used to compare paths that are associated
       * with different file system providers.
       *
       * @param   other  the path compared to this path.
       *
       * @return  zero if the argument is {@link #equals equal} to this path, a
       *          value less than zero if this path is lexicographically less than
       *          the argument, or a value greater than zero if this path is
       *          lexicographically greater than the argument
       *
       * @throws  ClassCastException
       *          if the paths are associated with different providers
       */
      @Override
      int compareTo(Path other);
  
      /**
       * Tests this path for equality with the given object.
       *
       * <p> If the given object is not a Path, or is a Path associated with a
       * different {@code FileSystem}, then this method returns {@code false}.
       *
       * <p> Whether or not two path are equal depends on the file system
       * implementation. In some cases the paths are compared without regard
       * to case, and others are case sensitive. This method does not access the
       * file system and the file is not required to exist. Where required, the
       * {@link Files#isSameFile isSameFile} method may be used to check if two
       * paths locate the same file.
       *
       * <p> This method satisfies the general contract of the {@link
       * Object#equals(Object) Object.equals} method. </p>
       *
       * @param   other
       *          the object to which this object is to be compared
       *
       * @return  {@code true} if, and only if, the given object is a {@code Path}
       *          that is identical to this {@code Path}
       */
      boolean equals(Object other);
  
      /**
       * Computes a hash code for this path.
       *
       * <p> The hash code is based upon the components of the path, and
       * satisfies the general contract of the {@link Object#hashCode
       * Object.hashCode} method.
       *
       * @return  the hash-code value for this path
       */
      int hashCode();
  
      /**
       * Returns the string representation of this path.
       *
       * <p> If this path was created by converting a path string using the
       * {@link FileSystem#getPath getPath} method then the path string returned
       * by this method may differ from the original String used to create the path.
       *
       * <p> The returned path string uses the default name {@link
       * FileSystem#getSeparator separator} to separate names in the path.
       *
       * @return  the string representation of this path
       */
      String toString();
  }
  