/*
 
* Copyright (c) 2007, 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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* questions.
 
*/

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 java.io.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 java.io.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 java.io.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
 
 
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
     
* java.lang.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();
}