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package java.nio.file;
import java.nio.file.attribute.*;
import java.nio.channels.SeekableByteChannel;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URI;
import java.util.Iterator;
import java.util.Set;
/**
* A file reference that locates a file using a system dependent path. The file
* is not required to exist.
*
* <p> On many platforms a <em>path</em> is the means to locate and access files
* in a file system. A path is hierarchical and composed of a sequence of
* directory and file name elements separated by a special separator or
* delimiter.
*
* <h4>Path operations</h4>
*
* <p> A system dependent path represented by this class is conceptually a
* sequence of name elements and optionally a <em>root component</em>. The name
* that is <em>farthest</em> from the root of the directory hierarchy is the
* name of a file or directory. The other elements are directory names. The root
* component typically identifies a file system hierarchy. A {@code Path} can
* represent a root, a root and a sequence of names, or simply one or more name
* elements. It defines the {@link #getName() getName}, {@link #getParent
* getParent}, {@link #getRoot getRoot}, and {@link #subpath subpath} methods
* to access the components or a subsequence of its name elements.
*
* <p> In addition to accessing the components of a path, a {@code Path} also
* defines {@link #resolve(Path) resolve} and {@link #relativize relativize}
* operations. Paths can also be {@link #compareTo compared}, and tested
* against each other using using the {@link #startsWith startsWith} and {@link
* #endsWith endWith} methods.
*
* <h4>File operations</h4>
*
* <p> A {@code Path} is either <em>absolute</em> or <em>relative</em>. An
* absolute path is complete in that does not need to be combined with another
* path in order to locate a file. All operations on relative paths are first
* resolved against a file system's default directory as if by invoking the
* {@link #toAbsolutePath toAbsolutePath} method.
*
* <p> In addition to the operations defined by the {@link FileRef} interface,
* this class defines the following operations:
*
* <ul>
* <li><p> The {@link #newByteChannel newByteChannel} method
* may be used to open a file and obtain a byte channel for reading or
* writing. </p></li>
* <li><p> Files may be {@link #createFile(FileAttribute[]) created}, or
* directories may be {@link #createDirectory(FileAttribute[]) created}.
* </p></li>
* <li><p> The {@link #delete delete} method may be used to delete a file.
* </p></li>
* <li><p> The {@link #checkAccess checkAccess} method may be used to check
* the existence or accessibility of a file. </p></li>
* <li><p> The {@link #isSameFile isSameFile} method may be used to test if
* two file references locate the same file. </p></li>
* <li><p> The {@link #getFileStore getFileStore} method may be used to
* obtain the {@link FileStore} representing the storage where a file is
* located. </p></li>
* <li><p> Directories can be {@link #newDirectoryStream opened} so as to
* iterate over the entries in the directory. </p></li>
* <li><p> Files can be {@link #copyTo(Path,CopyOption[]) copied} or
* {@link #moveTo(Path,CopyOption[]) moved}. </p></li>
* <li><p> Symbolic links may be {@link #createSymbolicLink created}, or the
* target of a symbolic link may be {@link #readSymbolicLink read}. </p></li>
* <li><p> The {@link #toRealPath real} path of an existing file may be
* obtained. </li></p>
* </ul>
*
* <p> This class implements {@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.
*
* <h4>File attributes</h4>
*
* In addition to the {@link #setAttribute setAttribute} and {@link #getAttribute
* getAttribute} methods, the <a href="attribute/package-summary.html">{@code
* java.nio.file.attribute}</a> package provides type-safe and efficient access
* to file attributes or <em>meta-data</em> associated with files. The {@link
* Attributes Attributes} class defines methods that operate on or return file
* attributes. For example, the file type, size, timestamps, and other
* <em>basic</em> meta-data are obtained, in bulk, by invoking the {@link
* Attributes#readBasicFileAttributes Attributes.readBasicFileAttributes} method:
* <pre>
* Path file = ...
* BasicFileAttributes attrs = Attributes.readBasicFileAttributes(file);
* </pre>
*
* <a name="interop"><h4>Interoperability</h4></a>
*
* <p> Paths created by file systems 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
* File.toPath} method may be used to obtain a {@code Path} from the abstract
* path name represented by a {@code java.io.File java.io.File} object. The
* resulting {@code Path} can be used to operate on the same file as the {@code
* java.io.File} object.
*
* <p> Path objects created by file systems associated with the default
* provider are interoperable with objects created by other file systems created
* by the same provider. Path objects created by file systems associated with
* other providers may not be interoperable with other file systems created by
* the same provider. The reasons for this are provider specific.
*
* <h4>Concurrency</h4></a>
*
* <p> Instances of this class are immutable and safe for use by multiple concurrent
* threads.
*
* @since 1.7
*/
public abstract class Path
implements FileRef, Comparable<Path>, Iterable<Path>, Watchable
{
/**
* Initializes a new instance of this class.
*/
protected Path() { }
/**
* Returns the file system that created this object.
*
* @return the file system that created this object
*/
public abstract 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
*/
public abstract 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}
*/
public abstract Path getRoot();
/**
* Returns the name of the file or directory denoted by this path. 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
*/
public abstract Path getName();
/**
* 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, getNameCount()-1);
* </pre></blockquote>
*
* @return a path representing the path's parent
*/
public abstract 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
*/
public abstract int getNameCount();
/**
* Returns a name element of this path.
*
* <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
*/
public abstract 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.
*/
public abstract 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.
*
* @param other
* the given path
*
* @return {@code true} if this path starts with the given path; otherwise
* {@code false}
*/
public abstract boolean startsWith(Path 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.
*
* @param other
* the given path
*
* @return {@code true} if this path ends with the given path; otherwise
* {@code false}
*/
public abstract boolean endsWith(Path 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 is it 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, or {@code null} if this path does not
* have a root component and all name elements are redundant
*
* @see #getParent
* @see #toRealPath
*/
public abstract 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 {@code null} then this path is returned. 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; can be {@code null}
*
* @return the resulting path
*
* @see #relativize
*/
public abstract 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.
*
* @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
*/
public abstract Path resolve(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 {@code null} is returned.
*
* <p> For any two 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 #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 {@code null} if both paths are
* equal
*
* @throws IllegalArgumentException
* if {@code other} is not a {@code Path} that can be relativized
* against this path
*/
public abstract Path relativize(Path other);
// -- file operations --
/**
* Deletes the file located by this path.
*
* <p> An implementation may require to examine the file to determine if the
* file is a directory. Consequently this method may not be atomic with respect
* to other file system operations. If the file is a symbolic link then the
* symbolic link itself, not the final target of the link, is deleted.
*
* <p> If the file is a directory then the directory must be empty. In some
* implementations a directory has entries for special files or links that
* are created when the directory is created. In such implementations a
* directory is considered empty when only the special entries exist.
*
* <p> On some operating systems it may not be possible to remove a file when
* it is open and in use by this Java virtual machine or other programs.
*
* @throws NoSuchFileException
* if the file does not exist <i>(optional specific exception)</i>
* @throws DirectoryNotEmptyException
* if the file is a directory and could not otherwise be deleted
* because the directory is not empty <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#checkDelete(String)} method
* is invoked to check delete access to the file
*/
public abstract void delete() throws IOException;
/**
* Deletes the file located by this path, if it exists.
*
* <p> As with the {@link #delete delete()} method, an implementation may
* need to examine the file to determine if the file is a directory.
* Consequently this method may not be atomic with respect to other file
* system operations. If the file is a symbolic link, then the symbolic
* link itself, not the final target of the link, is deleted.
*
* <p> If the file is a directory then the directory must be empty. In some
* implementations a directory has entries for special files or links that
* are created when the directory is created. In such implementations a
* directory is considered empty when only the special entries exist.
*
* <p> On some operating systems it may not be possible to remove a file when
* it is open and in use by this Java virtual machine or other programs.
*
* @throws DirectoryNotEmptyException
* if the file is a directory and could not otherwise be deleted
* because the directory is not empty <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#checkDelete(String)} method
* is invoked to check delete access to the file.
*/
public abstract void deleteIfExists() throws IOException;
/**
* Creates a symbolic link to a target <i>(optional operation)</i>.
*
* <p> The {@code target} parameter is the target of the link. It may be an
* {@link Path#isAbsolute absolute} or relative path and may not exist. When
* the target is a relative path then file system operations on the resulting
* link are relative to the path of the link.
*
* <p> The {@code attrs} parameter is an optional array of {@link FileAttribute
* attributes} to set atomically when creating the link. Each attribute is
* identified by its {@link FileAttribute#name name}. If more than one attribute
* of the same name is included in the array then all but the last occurrence
* is ignored.
*
* <p> Where symbolic links are supported, but the underlying {@link FileStore}
* does not support symbolic links, then this may fail with an {@link
* IOException}. Additionally, some operating systems may require that the
* Java virtual machine be started with implementation specific privileges to
* create symbolic links, in which case this method may throw {@code IOException}.
*
* @param target
* the target of the symbolic link
* @param attrs
* the array of attributes to set atomically when creating the
* symbolic link
*
* @return this path
*
* @throws UnsupportedOperationException
* if the implementation does not support symbolic links or the
* array contains an attribute that cannot be set atomically when
* creating the symbolic link
* @throws FileAlreadyExistsException
* if a file with the name already exists <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, it denies {@link LinkPermission}<tt>("symbolic")</tt>
* or its {@link SecurityManager#checkWrite(String) checkWrite}
* method denies write access to the path of the symbolic link.
*/
public abstract Path createSymbolicLink(Path target, FileAttribute<?>... attrs)
throws IOException;
/**
* Creates a new link (directory entry) for an existing file <i>(optional
* operation)</i>.
*
* <p> This path locates the directory entry to create. The {@code existing}
* parameter is the path to an existing file. This method creates a new
* directory entry for the file so that it can be accessed using this path.
* On some file systems this is known as creating a "hard link". Whether the
* file attributes are maintained for the file or for each directory entry
* is file system specific and therefore not specified. Typically, a file
* system requires that all links (directory entries) for a file be on the
* same file system. Furthermore, on some platforms, the Java virtual machine
* may require to be started with implementation specific privileges to
* create hard links or to create links to directories.
*
* @param existing
* a reference to an existing file
*
* @return this path
*
* @throws UnsupportedOperationException
* if the implementation does not support adding an existing file
* to a directory
* @throws FileAlreadyExistsException
* if the entry could not otherwise be created because a file of
* that name already exists <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, it denies {@link LinkPermission}<tt>("hard")</tt>
* or its {@link SecurityManager#checkWrite(String) checkWrite}
* method denies write access to both this path and the path of the
* existing file.
*/
public abstract Path createLink(Path existing) throws IOException;
/**
* Reads the target of a symbolic link <i>(optional operation)</i>.
*
* <p> If the file system supports <a href="package-summary.html#links">symbolic
* links</a> then this method is used to read the target of the link, failing
* if the file is not a symbolic link. The target of the link need not exist.
* The returned {@code Path} object will be associated with the same file
* system as this {@code Path}.
*
* @return a {@code Path} object representing the target of the link
*
* @throws UnsupportedOperationException
* if the implementation does not support symbolic links
* @throws NotLinkException
* if the target could otherwise not be read because the file
* is not a symbolic link <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, it checks that {@code FilePermission} has been
* granted with the "{@code readlink}" action to read the link.
*/
public abstract Path readSymbolicLink() throws IOException;
/**
* Returns a URI to represent this path.
*
* <p> This method constructs a hierarchical {@link URI} that is absolute
* with a non-empty path component. Its {@link URI#getScheme() scheme} is
* equal to the URI scheme that identifies the provider. The exact form of
* the other URI components is highly provider dependent. In particular, it
* is implementation dependent if its query, fragment, and authority
* components are defined or undefined.
*
* <p> For the default provider the {@link URI#getPath() path} component
* will represent the {@link #toAbsolutePath absolute} path; the query,
* 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 {@link java.io.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 an absolute, hierarchical URI with a non-empty path component
*
* @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.
*/
public abstract 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 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}
*/
public abstract 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 #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 resolveLinks} parameter specifies if symbolic links
* should be resolved. This parameter is ignored when symbolic links are
* not supported. Where supported, and the parameter has the value {@code
* true} then symbolic links are resolved to their final target. Where the
* parameter has the value {@code false} 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 causes 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.
*
* @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}
*/
public abstract Path toRealPath(boolean resolveLinks) throws IOException;
/**
* Copy the file located by this path to a target location.
*
* <p> This method copies the file located by this {@code Path} to the
* target location with the {@code options} parameter specifying how the
* copy is performed. By default, the copy fails if the target file already
* exists, except if the source and target are the {@link #isSameFile same}
* file, in which case this method has no effect. File attributes are not
* required to be copied to the target file. If symbolic links are supported,
* and the file is a symbolic link, then the final target of the link is copied.
* If the file is a directory then it creates an empty directory in the target
* location (entries in the directory are not copied). This method can be
* used with the {@link Files#walkFileTree Files.walkFileTree} utility
* method to copy a directory and all entries in the directory, or an entire
* <i>file-tree</i> where required.
*
* <p> The {@code options} parameter is an array of options and may contain
* any of the following:
*
* <table border=1 cellpadding=5 summary="">
* <tr> <th>Option</th> <th>Description</th> </tr>
* <tr>
* <td> {@link StandardCopyOption#REPLACE_EXISTING REPLACE_EXISTING} </td>
* <td> If the target file exists, then the target file is replaced if it
* is not a non-empty directory. If the target file exists and is a
* symbolic link, then the symbolic link itself, not the target of
* the link, is replaced. </td>
* </tr>
* <tr>
* <td> {@link StandardCopyOption#COPY_ATTRIBUTES COPY_ATTRIBUTES} </td>
* <td> Attempts to copy the file attributes associated with this file to
* the target file. The exact file attributes that are copied is platform
* and file system dependent and therefore unspecified. Minimally, the
* {@link BasicFileAttributes#lastModifiedTime last-modified-time} is
* copied to the target file if supported by both the source and target
* file store. Copying of file timestamps may result in precision
* loss. </td>
* </tr>
* <tr>
* <td> {@link LinkOption#NOFOLLOW_LINKS NOFOLLOW_LINKS} </td>
* <td> Symbolic links are not followed. If the file, located by this path,
* is a symbolic link, then the symbolic link itself, not the target of
* the link, is copied. It is implementation specific if file attributes
* can be copied to the new link. In other words, the {@code
* COPY_ATTRIBUTES} option may be ignored when copying a symbolic link. </td>
* </tr>
* </table>
*
* <p> An implementation of this interface may support additional
* implementation specific options.
*
* <p> Copying a file is not an atomic operation. If an {@link IOException}
* is thrown then it possible that the target file is incomplete or some of
* its file attributes have not been copied from the source file. When the
* {@code REPLACE_EXISTING} option is specified and the target file exists,
* then the target file is replaced. The check for the existence of the file
* and the creation of the new file may not be atomic with respect to other
* file system activities.
*
* @param target
* the target location
* @param options
* options specifying how the copy should be done
*
* @return the target
*
* @throws UnsupportedOperationException
* if the array contains a copy option that is not supported
* @throws FileAlreadyExistsException
* if the target file exists and cannot be replaced because the
* {@code REPLACE_EXISTING} option is not specified, or the target
* file is a non-empty 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 source file, the
* {@link SecurityManager#checkWrite(String) checkWrite} is invoked
* to check write access to the target file. If a symbolic link is
* copied the security manager is invoked to check {@link
* LinkPermission}{@code ("symbolic")}.
*/
public abstract Path copyTo(Path target, CopyOption... options)
throws IOException;
/**
* Move or rename the file located by this path to a target location.
*
* <p> By default, this method attempts to move the file to the target
* location, failing if the target file exists except if the source and
* target are the {@link #isSameFile same} file, in which case this method
* has no effect. If the file is a symbolic link then the symbolic link
* itself, not the target of the link, is moved. This method may be
* invoked to move an empty directory. In some implementations a directory
* has entries for special files or links that are created when the
* directory is created. In such implementations a directory is considered
* empty when only the special entries exist. When invoked to move a
* directory that is not empty then the directory is moved if it does not
* require moving the entries in the directory. For example, renaming a
* directory on the same {@link FileStore} will usually not require moving
* the entries in the directory. When moving a directory requires that its
* entries be moved then this method fails (by throwing an {@code
* IOException}). To move a <i>file tree</i> may involve copying rather
* than moving directories and this can be done using the {@link
* #copyTo copyTo} method in conjunction with the {@link
* Files#walkFileTree Files.walkFileTree} utility method.
*
* <p> The {@code options} parameter is an array of options and may contain
* any of the following:
*
* <table border=1 cellpadding=5 summary="">
* <tr> <th>Option</th> <th>Description</th> </tr>
* <tr>
* <td> {@link StandardCopyOption#REPLACE_EXISTING REPLACE_EXISTING} </td>
* <td> If the target file exists, then the target file is replaced if it
* is not a non-empty directory. If the target file exists and is a
* symbolic link, then the symbolic link itself, not the target of
* the link, is replaced. </td>
* </tr>
* <tr>
* <td> {@link StandardCopyOption#ATOMIC_MOVE ATOMIC_MOVE} </td>
* <td> The move is performed as an atomic file system operation and all
* other options are ignored. If the target file exists then it is
* implementation specific if the existing file is replaced or this method
* fails by throwing an {@link IOException}. If the move cannot be
* performed as an atomic file system operation then {@link
* AtomicMoveNotSupportedException} is thrown. This can arise, for
* example, when the target location is on a different {@code FileStore}
* and would require that the file be copied, or target location is
* associated with a different provider to this object. </td>
* </table>
*
* <p> An implementation of this interface may support additional
* implementation specific options.
*
* <p> Where the move requires that the file be copied then the {@link
* BasicFileAttributes#lastModifiedTime last-modified-time} is copied to the
* new file. An implementation may also attempt to copy other file
* attributes but is not required to fail if the file attributes cannot be
* copied. When the move is performed as a non-atomic operation, and a {@code
* IOException} is thrown, then the state of the files is not defined. The
* original file and the target file may both exist, the target file may be
* incomplete or some of its file attributes may not been copied from the
* original file.
*
* @param target
* the target location
* @param options
* options specifying how the move should be done
*
* @return the target
*
* @throws UnsupportedOperationException
* if the array contains a copy option that is not supported
* @throws FileAlreadyExistsException
* if the target file exists and cannot be replaced because the
* {@code REPLACE_EXISTING} option is not specified, or the target
* file is a non-empty directory
* @throws AtomicMoveNotSupportedException
* if the options array contains the {@code ATOMIC_MOVE} option but
* the file cannot be moved as an atomic file system operation.
* @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#checkWrite(String) checkWrite}
* method is invoked to check write access to both the source and
* target file.
*/
public abstract Path moveTo(Path target, CopyOption... options)
throws IOException;
/**
* Opens the directory referenced by this object, returning a {@code
* DirectoryStream} to iterate over all entries in the directory. The
* elements returned by the directory stream's {@link DirectoryStream#iterator
* iterator} are of type {@code Path}, each one representing an entry in the
* directory. The {@code Path} objects are obtained as if by {@link
* #resolve(Path) resolving} the name of the directory entry against this
* path.
*
* <p> The directory stream's {@code close} method should be invoked after
* iteration is completed so as to free any resources held for the open
* directory.
*
* <p> When an implementation supports operations on entries in the
* directory that execute in a race-free manner then the returned directory
* stream is a {@link SecureDirectoryStream}.
*
* @return a new and open {@code DirectoryStream} object
*
* @throws NotDirectoryException
* if the file could not otherwise be opened because it 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 directory.
*/
public abstract DirectoryStream<Path> newDirectoryStream()
throws IOException;
/**
* Opens the directory referenced by this object, returning a {@code
* DirectoryStream} to iterate over the entries in the directory. The
* elements returned by the directory stream's {@link DirectoryStream#iterator
* iterator} are of type {@code Path}, each one representing an entry in the
* directory. The {@code Path} objects are obtained as if by {@link
* #resolve(Path) resolving} the name of the directory entry against this
* path. The entries returned by the iterator are filtered by matching the
* {@code String} representation of their file names against the given
* <em>globbing</em> pattern.
*
* <p> For example, suppose we want to iterate over the files ending with
* ".java" in a directory:
* <pre>
* Path dir = ...
* DirectoryStream<Path> stream = dir.newDirectoryStream("*.java");
* </pre>
*
* <p> The globbing pattern is specified by the {@link
* FileSystem#getPathMatcher getPathMatcher} method.
*
* <p> The directory stream's {@code close} method should be invoked after
* iteration is completed so as to free any resources held for the open
* directory.
*
* <p> When an implementation supports operations on entries in the
* directory that execute in a race-free manner then the returned directory
* stream is a {@link SecureDirectoryStream}.
*
* @param glob
* the glob pattern
*
* @return a new and open {@code DirectoryStream} object
*
* @throws java.util.regex.PatternSyntaxException
* if the pattern is invalid
* @throws NotDirectoryException
* if the file could not otherwise be opened because it 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 directory.
*/
public abstract DirectoryStream<Path> newDirectoryStream(String glob)
throws IOException;
/**
* Opens the directory referenced by this object, returning a {@code
* DirectoryStream} to iterate over the entries in the directory. The
* elements returned by the directory stream's {@link DirectoryStream#iterator
* iterator} are of type {@code Path}, each one representing an entry in the
* directory. The {@code Path} objects are obtained as if by {@link
* #resolve(Path) resolving} the name of the directory entry against this
* path. The entries returned by the iterator are filtered by the given
* {@link DirectoryStream.Filter filter}.
*
* <p> The directory stream's {@code close} method should be invoked after
* iteration is completed so as to free any resources held for the open
* directory.
*
* <p> Where the filter terminates due to an uncaught error or runtime
* exception then it is propagated to the {@link Iterator#hasNext()
* hasNext} or {@link Iterator#next() next} method. Where an {@code
* IOException} is thrown, it results in the {@code hasNext} or {@code
* next} method throwing a {@link DirectoryIteratorException} with the
* {@code IOException} as the cause.
*
* <p> When an implementation supports operations on entries in the
* directory that execute in a race-free manner then the returned directory
* stream is a {@link SecureDirectoryStream}.
*
* <p> <b>Usage Example:</b>
* Suppose we want to iterate over the files in a directory that are
* larger than 8K.
* <pre>
* DirectoryStream.Filter<Path> filter = new DirectoryStream.Filter<Path>() {
* public boolean accept(Path file) throws IOException {
* long size = Attributes.readBasicFileAttributes(file).size();
* return (size > 8192L);
* }
* };
* Path dir = ...
* DirectoryStream<Path> stream = dir.newDirectoryStream(filter);
* </pre>
* @param filter
* the directory stream filter
*
* @return a new and open {@code DirectoryStream} object
*
* @throws NotDirectoryException
* if the file could not otherwise be opened because it 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 directory.
*/
public abstract DirectoryStream<Path> newDirectoryStream(DirectoryStream.Filter<? super Path> filter)
throws IOException;
/**
* Creates a new and empty file, failing if the file already exists.
*
* <p> This {@code Path} locates the file to create. The check for the
* existence of the file and the creation of the new file if it does not
* exist are a single operation that is atomic with respect to all other
* filesystem activities that might affect the directory.
*
* <p> The {@code attrs} parameter is an optional array of {@link FileAttribute
* file-attributes} to set atomically when creating the file. Each attribute
* is identified by its {@link FileAttribute#name name}. If more than one
* attribute of the same name is included in the array then all but the last
* occurrence is ignored.
*
* @param attrs
* an optional list of file attributes to set atomically when
* creating the file
*
* @return this path
*
* @throws UnsupportedOperationException
* if the array contains an attribute that cannot be set atomically
* when creating the file
* @throws FileAlreadyExistsException
* if a file of that name already exists
* <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#checkWrite(String) checkWrite}
* method is invoked to check write access to the new file.
*/
public abstract Path createFile(FileAttribute<?>... attrs) throws IOException;
/**
* Creates a new directory.
*
* <p> This {@code Path} locates the directory to create. The check for the
* existence of the file and the creation of the directory if it does not
* exist are a single operation that is atomic with respect to all other
* filesystem activities that might affect the directory.
*
* <p> The {@code attrs} parameter is an optional array of {@link FileAttribute
* file-attributes} to set atomically when creating the directory. Each
* file attribute is identified by its {@link FileAttribute#name name}. If
* more than one attribute of the same name is included in the array then all
* but the last occurrence is ignored.
*
* @param attrs
* an optional list of file attributes to set atomically when
* creating the directory
*
* @return this path
*
* @throws UnsupportedOperationException
* if the array contains an attribute that cannot be set atomically
* when creating the directory
* @throws FileAlreadyExistsException
* if a directory could not otherwise be created because a file of
* that name already exists <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#checkWrite(String) checkWrite}
* method is invoked to check write access to the new directory.
*
* @see Files#createDirectories
*/
public abstract Path createDirectory(FileAttribute<?>... attrs)
throws IOException;
/**
* Opens or creates a file, returning a seekable byte channel to access the
* file.
*
* <p> The {@code options} parameter determines how the file is opened.
* The {@link StandardOpenOption#READ READ} and {@link StandardOpenOption#WRITE WRITE}
* options determine if the file should be opened for reading and/or writing.
* If neither option (or the {@link StandardOpenOption#APPEND APPEND}
* option) is contained in the array then the file is opened for reading.
* By default reading or writing commences at the beginning of the file.
*
* <p> In the addition to {@code READ} and {@code WRITE}, the following
* options may be present:
*
* <table border=1 cellpadding=5 summary="">
* <tr> <th>Option</th> <th>Description</th> </tr>
* <tr>
* <td> {@link StandardOpenOption#APPEND APPEND} </td>
* <td> If this option is present then the file is opened for writing and
* each invocation of the channel's {@code write} method first advances
* the position to the end of the file and then writes the requested
* data. Whether the advancement of the position and the writing of the
* data are done in a single atomic operation is system-dependent and
* therefore unspecified. This option may not be used in conjunction
* with the {@code READ} or {@code TRUNCATE_EXISTING} options. </td>
* </tr>
* <tr>
* <td> {@link StandardOpenOption#TRUNCATE_EXISTING TRUNCATE_EXISTING} </td>
* <td> If this option is present then the existing file is truncated to
* a size of 0 bytes. This option is ignored when the file is opened only
* for reading. </td>
* </tr>
* <tr>
* <td> {@link StandardOpenOption#CREATE_NEW CREATE_NEW} </td>
* <td> If this option is present then a new file is created, failing if
* the file already exists or is a symbolic link. When creating a file the
* check for the existence of the file and the creation of the file if it
* does not exist is atomic with respect to other file system operations.
* This option is ignored when the file is opened only for reading. </td>
* </tr>
* <tr>
* <td > {@link StandardOpenOption#CREATE CREATE} </td>
* <td> If this option is present then an existing file is opened if it
* exists, otherwise a new file is created. This option is ignored if the
* {@code CREATE_NEW} option is also present or the file is opened only
* for reading. </td>
* </tr>
* <tr>
* <td > {@link StandardOpenOption#DELETE_ON_CLOSE DELETE_ON_CLOSE} </td>
* <td> When this option is present then the implementation makes a
* <em>best effort</em> attempt to delete the file when closed by the
* {@link SeekableByteChannel#close close} method. If the {@code close}
* method is not invoked then a <em>best effort</em> attempt is made to
* delete the file when the Java virtual machine terminates. </td>
* </tr>
* <tr>
* <td>{@link StandardOpenOption#SPARSE SPARSE} </td>
* <td> When creating a new file this option is a <em>hint</em> that the
* new file will be sparse. This option is ignored when not creating
* a new file. </td>
* </tr>
* <tr>
* <td> {@link StandardOpenOption#SYNC SYNC} </td>
* <td> Requires that every update to the file's content or metadata be
* written synchronously to the underlying storage device. (see <a
* href="package-summary.html#integrity"> Synchronized I/O file
* integrity</a>). </td>
* <tr>
* <tr>
* <td> {@link StandardOpenOption#DSYNC DSYNC} </td>
* <td> Requires that every update to the file's content be written
* synchronously to the underlying storage device. (see <a
* href="package-summary.html#integrity"> Synchronized I/O file
* integrity</a>). </td>
* </tr>
* </table>
*
* <p> An implementation may also support additional implementation specific
* options.
*
* <p> The {@code attrs} parameter is an optional array of file {@link
* FileAttribute file-attributes} to set atomically when a new file is created.
*
* <p> In the case of the default provider, the returned seekable byte channel
* is a {@link java.nio.channels.FileChannel}.
*
* <p> <b>Usage Examples:</b>
* <pre>
* Path file = ...
*
* // open file for reading
* ReadableByteChannel rbc = file.newByteChannel(EnumSet.of(READ)));
*
* // open file for writing to the end of an existing file, creating
* // the file if it doesn't already exist
* WritableByteChannel wbc = file.newByteChannel(EnumSet.of(CREATE,APPEND));
*
* // create file with initial permissions, opening it for both reading and writing
* FileAttribute<Set<PosixFilePermission>> perms = ...
* SeekableByteChannel sbc = file.newByteChannel(EnumSet.of(CREATE_NEW,READ,WRITE), perms);
* </pre>
*
* @param options
* Options specifying how the file is opened
* @param attrs
* An optional list of file attributes to set atomically when
* creating the file
*
* @return a new seekable byte channel
*
* @throws IllegalArgumentException
* if the set contains an invalid combination of options
* @throws UnsupportedOperationException
* if an unsupported open option is specified or the array contains
* attributes that cannot be set atomically when creating the file
* @throws FileAlreadyExistsException
* if a file of that name already exists and the {@link
* StandardOpenOption#CREATE_NEW CREATE_NEW} option is specified
* <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 path if the file is
* opened for reading. The {@link SecurityManager#checkWrite(String)
* checkWrite} method is invoked to check write access to the path
* if the file is opened for writing.
*/
public abstract SeekableByteChannel newByteChannel(Set<? extends OpenOption> options,
FileAttribute<?>... attrs)
throws IOException;
/**
* Opens or creates a file, returning a seekable byte channel to access the
* file.
*
* <p> This method opens or creates a file in exactly the manner specified
* by the {@link Path#newByteChannel(Set,FileAttribute[]) newByteChannel}
* method.
*
* @param options
* options specifying how the file is opened
*
* @return a new seekable byte channel
*
* @throws IllegalArgumentException
* if the set contains an invalid combination of options
* @throws UnsupportedOperationException
* if an unsupported open option is specified
* @throws FileAlreadyExistsException
* if a file of that name already exists and the {@link
* StandardOpenOption#CREATE_NEW CREATE_NEW} option is specified
* <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 path if the file is
* opened for reading. The {@link SecurityManager#checkWrite(String)
* checkWrite} method is invoked to check write access to the path
* if the file is opened for writing.
*/
public abstract SeekableByteChannel newByteChannel(OpenOption... options)
throws IOException;
/**
* Opens or creates the file located by this object for writing, returning
* an output stream to write bytes to the file.
*
* <p> This method opens or creates a file in exactly the manner specified
* by the {@link Path#newByteChannel(Set,FileAttribute[]) newByteChannel}
* method except that the {@link StandardOpenOption#READ READ} option may not
* be present in the array of open options.
*
* @param options
* options specifying how the file is opened
*
* @return a new output stream
*
* @throws IllegalArgumentException {@inheritDoc}
* @throws UnsupportedOperationException {@inheritDoc}
* @throws IOException {@inheritDoc}
* @throws SecurityException {@inheritDoc}
*/
@Override
public abstract OutputStream newOutputStream(OpenOption... options)
throws IOException;
/**
* Tells whether or not the file located by this object is considered
* <em>hidden</em>. The exact definition of hidden is platform or provider
* dependent. On UNIX for example a file is considered to be hidden if its
* name begins with a period character ('.'). On Windows a file is
* considered hidden if it isn't a directory and the DOS {@link
* DosFileAttributes#isHidden hidden} attribute is set.
*
* <p> Depending on the implementation this method may require to access
* the file system to determine if the file is considered hidden.
*
* @return {@code true} if the file is considered hidden
*
* @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.
*/
public abstract boolean isHidden() throws IOException;
/**
* Checks the existence and optionally the accessibility of the file
* located by this path.
*
* <p> This method checks the existence of a file and that this Java virtual
* machine has appropriate privileges that would allow it access the file
* according to all of access modes specified in the {@code modes} parameter
* as follows:
*
* <table border=1 cellpadding=5 summary="">
* <tr> <th>Value</th> <th>Description</th> </tr>
* <tr>
* <td> {@link AccessMode#READ READ} </td>
* <td> Checks that the file exists and that the Java virtual machine has
* permission to read the file. </td>
* </tr>
* <tr>
* <td> {@link AccessMode#WRITE WRITE} </td>
* <td> Checks that the file exists and that the Java virtual machine has
* permission to write to the file, </td>
* </tr>
* <tr>
* <td> {@link AccessMode#EXECUTE EXECUTE} </td>
* <td> Checks that the file exists and that the Java virtual machine has
* permission to {@link Runtime#exec execute} the file. The semantics
* may differ when checking access to a directory. For example, on UNIX
* systems, checking for {@code EXECUTE} access checks that the Java
* virtual machine has permission to search the directory in order to
* access file or subdirectories. </td>
* </tr>
* </table>
*
* <p> If the {@code modes} parameter is of length zero, then the existence
* of the file is checked.
*
* <p> This method follows symbolic links if the file referenced by this
* object is a symbolic link. Depending on the implementation, this method
* may require to read file permissions, access control lists, or other
* file attributes in order to check the effective access to the file. To
* determine the effective access to a file may require access to several
* attributes and so in some implementations this method may not be atomic
* with respect to other file system operations. Furthermore, as the result
* of this method is immediately outdated, there is no guarantee that a
* subsequence access will succeed (or even that it will access the same
* file). Care should be taken when using this method in security sensitive
* applications.
*
* @param modes
* The access modes to check; may have zero elements
*
* @throws UnsupportedOperationException
* an implementation is required to support checking for
* {@code READ}, {@code WRITE}, and {@code EXECUTE} access. This
* exception is specified to allow for the {@code Access} enum to
* be extended in future releases.
* @throws NoSuchFileException
* if a file does not exist <i>(optional specific exception)</i>
* @throws AccessDeniedException
* the requested access would be denied or the access cannot be
* determined because the Java virtual machine has insufficient
* privileges or other reasons. <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}
* is invoked when checking read access to the file or only the
* existence of the file, the {@link SecurityManager#checkWrite(String)
* checkWrite} is invoked when checking write access to the file,
* and {@link SecurityManager#checkExec(String) checkExec} is invoked
* when checking execute access.
*/
public abstract void checkAccess(AccessMode... modes) throws IOException;
/**
* Tests whether the file located by this path exists.
*
* <p> This convenience method is intended for cases where it is required to
* take action when it can be confirmed that a file exists. This method simply
* invokes the {@link #checkAccess checkAccess} method to check if the file
* exists. If the {@code checkAccess} method succeeds then this method returns
* {@code true}, otherwise if an {@code IOException} is thrown (because the
* file doesn't exist or cannot be accessed by this Java virtual machine)
* then {@code false} is returned.
*
* <p> Note that the result of this method is immediately outdated. If this
* method indicates the file exists then there is no guarantee that a
* subsequence access will succeed. Care should be taken when using this
* method in security sensitive applications.
*
* @return {@code true} if the file exists; {@code false} if the file does
* not exist or its existence cannot be determined.
*
* @throws SecurityException
* In the case of the default provider, the {@link
* SecurityManager#checkRead(String)} is invoked to check
* read access to the file.
*
* @see #notExists
*/
public abstract boolean exists();
/**
* Tests whether the file located by this path does not exist.
*
* <p> This convenience method is intended for cases where it is required to
* take action when it can be confirmed that a file does not exist. This
* method invokes the {@link #checkAccess checkAccess} method to check if the
* file exists. If the file does not exist then {@code true} is returned,
* otherwise the file exists or cannot be accessed by this Java virtual
* machine and {@code false} is returned.
*
* <p> Note that this method is not the complement of the {@link #exists
* exists} method. Where it is not possible to determine if a file exists
* or not then both methods return {@code false}. As with the {@code exists}
* method, the result of this method is immediately outdated. If this
* method indicates the file does exist then there is no guarantee that a
* subsequence attempt to create the file will succeed. Care should be taken
* when using this method in security sensitive applications.
*
* @return {@code true} if the file does not exist; {@code false} if the
* file exists or its existence cannot be determined.
*
* @throws SecurityException
* In the case of the default provider, the {@link
* SecurityManager#checkRead(String)} is invoked to check
* read access to the file.
*/
public abstract boolean notExists();
/**
* Returns the {@link FileStore} representing the file store where an
* existing file, located by this path, is stored.
*
* <p> Once a reference to the {@code FileStore} is obtained it is
* implementation specific if operations on the returned {@code FileStore},
* or {@link FileStoreAttributeView} objects obtained from it, continue
* to depend on the existence of the file. In particular the behavior is not
* defined for the case that the file is deleted or moved to a different
* file store.
*
* @return the file store where the file is stored
*
* @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, and in
* addition it checks {@link RuntimePermission}<tt>
* ("getFileStoreAttributes")</tt>
*/
public abstract FileStore getFileStore() throws IOException;
// -- 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 an array of
* events to register and may contain the following events:
* <ul>
* <li>{@link StandardWatchEventKind#ENTRY_CREATE ENTRY_CREATE} -
* entry created or moved into the directory</li>
* <li>{@link StandardWatchEventKind#ENTRY_DELETE ENTRY_DELETE} -
* entry deleted or moved out of the directory</li>
* <li>{@link StandardWatchEventKind#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 StandardWatchEventKind}
*
* <p> The {@code modifiers} parameter is an array of <em>modifiers</em>
* that qualify how the directory is registered. This release does not
* define any <em>standard</em> modifiers. The array 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
public abstract 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
public abstract 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
public abstract 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.
*
* @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
*/
@Override
public abstract int compareTo(Path other);
/**
* Tests if the file referenced by this object is the same file referenced
* by another object.
*
* <p> If this {@code Path} and the given {@code Path} are {@link
* #equals(Object) equal} then this method returns {@code true} without checking
* if the file exists. If the {@code Path} and the given {@code Path}
* are associated with different providers, or the given {@code Path} is
* {@code null} then this method returns {@code false}. Otherwise, this method
* checks if both {@code Paths} locate the same file, and depending on the
* implementation, may require to open or access both files.
*
* <p> If the file system and files remain static, then this method implements
* an equivalence relation for non-null {@code Paths}.
* <ul>
* <li>It is <i>reflexive</i>: for a non-null {@code Path} {@code f},
* {@code f.isSameFile(f)} should return {@code true}.
* <li>It is <i>symmetric</i>: for two non-null {@code Path}
* {@code f} and {@code g}, {@code f.isSameFile(g)} will equal
* {@code g.isSameFile(f)}.
* <li>It is <i>transitive</i>: for three {@code Paths}
* {@code f}, {@code g}, and {@code h}, if {@code f.isSameFile(g)} returns
* {@code true} and {@code g.isSameFile(h)} returns {@code true}, then
* {@code f.isSameFile(h)} will return return {@code true}.
* </ul>
*
* @param other
* the other file reference
*
* @return {@code true} if, and only if, this object and the given object
* locate the same file
*
* @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 both files.
*
* @see java.nio.file.attribute.BasicFileAttributes#fileKey
*/
public abstract boolean isSameFile(Path other) throws IOException;
/**
* 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 provider, then this method immediately 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.
*
* <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}
*/
@Override
public abstract 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
*/
@Override
public abstract 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
*/
@Override
public abstract String toString();
}