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	/*
	* Copyright (c) 1994, 2021, 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
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.io;

	import java.net.URI;
	import java.net.URL;
	import java.net.MalformedURLException;
	import java.net.URISyntaxException;
	import java.nio.file.FileStore;
	import java.nio.file.FileSystems;
	import java.nio.file.Path;
	import java.security.SecureRandom;
	import java.util.ArrayList;
	import java.util.List;
	import sun.security.action.GetPropertyAction;

	/**
	* An abstract representation of file and directory pathnames.
	*
	* <p> User interfaces and operating systems use system-dependent <em>pathname
	* strings</em> to name files and directories. This class presents an
	* abstract, system-independent view of hierarchical pathnames. An
	* <em>abstract pathname</em> has two components:
	*
	* <ol>
	* <li> An optional system-dependent <em>prefix</em> string,
	* such as a disk-drive specifier, {@code "/"} for the UNIX root
	* directory, or {@code "\\\\"} for a Microsoft Windows UNC pathname, and
	* <li> A sequence of zero or more string <em>names</em>.
	* </ol>
	*
	* The first name in an abstract pathname may be a directory name or, in the
	* case of Microsoft Windows UNC pathnames, a hostname. Each subsequent name
	* in an abstract pathname denotes a directory; the last name may denote
	* either a directory or a file. The <em>empty</em> abstract pathname has no
	* prefix and an empty name sequence.
	*
	* <p> The conversion of a pathname string to or from an abstract pathname is
	* inherently system-dependent. When an abstract pathname is converted into a
	* pathname string, each name is separated from the next by a single copy of
	* the default <em>separator character</em>. The default name-separator
	* character is defined by the system property {@code file.separator}, and
	* is made available in the public static fields {@link
	* #separator} and {@link #separatorChar} of this class.
	* When a pathname string is converted into an abstract pathname, the names
	* within it may be separated by the default name-separator character or by any
	* other name-separator character that is supported by the underlying system.
	*
	* <p> A pathname, whether abstract or in string form, may be either
	* <em>absolute</em> or <em>relative</em>. An absolute pathname is complete in
	* that no other information is required in order to locate the file that it
	* denotes. A relative pathname, in contrast, must be interpreted in terms of
	* information taken from some other pathname. By default the classes in the
	* {@code java.io} package always resolve relative pathnames against the
	* current user directory. This directory is named by the system property
	* {@code user.dir}, and is typically the directory in which the Java
	* virtual machine was invoked.
	*
	* <p> The <em>parent</em> of an abstract pathname may be obtained by invoking
	* the {@link #getParent} method of this class and consists of the pathname's
	* prefix and each name in the pathname's name sequence except for the last.
	* Each directory's absolute pathname is an ancestor of any {@code File}
	* object with an absolute abstract pathname which begins with the directory's
	* absolute pathname. For example, the directory denoted by the abstract
	* pathname {@code "/usr"} is an ancestor of the directory denoted by the
	* pathname {@code "/usr/local/bin"}.
	*
	* <p> The prefix concept is used to handle root directories on UNIX platforms,
	* and drive specifiers, root directories and UNC pathnames on Microsoft Windows platforms,
	* as follows:
	*
	* <ul>
	*
	* <li> For UNIX platforms, the prefix of an absolute pathname is always
	* {@code "/"}. Relative pathnames have no prefix. The abstract pathname
	* denoting the root directory has the prefix {@code "/"} and an empty
	* name sequence.
	*
	* <li> For Microsoft Windows platforms, the prefix of a pathname that contains a drive
	* specifier consists of the drive letter followed by {@code ":"} and
	* possibly followed by {@code "\\"} if the pathname is absolute. The
	* prefix of a UNC pathname is {@code "\\\\"}; the hostname and the share
	* name are the first two names in the name sequence. A relative pathname that
	* does not specify a drive has no prefix.
	*
	* </ul>
	*
	* <p> Instances of this class may or may not denote an actual file-system
	* object such as a file or a directory. If it does denote such an object
	* then that object resides in a <i>partition</i>. A partition is an
	* operating system-specific portion of storage for a file system. A single
	* storage device (e.g. a physical disk-drive, flash memory, CD-ROM) may
	* contain multiple partitions. The object, if any, will reside on the
	* partition <a id="partName">named</a> by some ancestor of the absolute
	* form of this pathname.
	*
	* <p> A file system may implement restrictions to certain operations on the
	* actual file-system object, such as reading, writing, and executing. These
	* restrictions are collectively known as <i>access permissions</i>. The file
	* system may have multiple sets of access permissions on a single object.
	* For example, one set may apply to the object's <i>owner</i>, and another
	* may apply to all other users. The access permissions on an object may
	* cause some methods in this class to fail.
	*
	* <p> Instances of the {@code File} class are immutable; that is, once
	* created, the abstract pathname represented by a {@code File} object
	* will never change.
	*
	* <h2>Interoperability with {@code java.nio.file} package</h2>
	*
	* <p> The <a href="../../java/nio/file/package-summary.html">{@code java.nio.file}</a>
	* package defines interfaces and classes for the Java virtual machine to access
	* files, file attributes, and file systems. This API may be used to overcome
	* many of the limitations of the {@code java.io.File} class.
	* The {@link #toPath toPath} method may be used to obtain a {@link
	* Path} that uses the abstract path represented by a {@code File} object to
	* locate a file. The resulting {@code Path} may be used with the {@link
	* java.nio.file.Files} class to provide more efficient and extensive access to
	* additional file operations, file attributes, and I/O exceptions to help
	* diagnose errors when an operation on a file fails.
	*
	* @since 1.0
	*/

	public class File
	implements Serializable, Comparable<File>
	{

	/**
	* The FileSystem object representing the platform's local file system.
	*/
	private static final FileSystem fs = DefaultFileSystem.getFileSystem();

	/**
	* This abstract pathname's normalized pathname string. A normalized
	* pathname string uses the default name-separator character and does not
	* contain any duplicate or redundant separators.
	*
	* @serial
	*/
	private final String path;

	/**
	* Enum type that indicates the status of a file path.
	*/
	private static enum PathStatus { INVALID, CHECKED };

	/**
	* The flag indicating whether the file path is invalid.
	*/
	private transient PathStatus status = null;

	/**
	* Check if the file has an invalid path. Currently, the inspection of
	* a file path is very limited, and it only covers Nul character check.
	* Returning true means the path is definitely invalid/garbage. But
	* returning false does not guarantee that the path is valid.
	*
	* @return true if the file path is invalid.
	*/
	final boolean isInvalid() {
	PathStatus s = status;
	if (s == null) {
	s = (this.path.indexOf('\u0000') < 0) ? PathStatus.CHECKED
	: PathStatus.INVALID;
	status = s;
	}
	return s == PathStatus.INVALID;
	}

	/**
	* The length of this abstract pathname's prefix, or zero if it has no
	* prefix.
	*/
	private final transient int prefixLength;

	/**
	* Returns the length of this abstract pathname's prefix.
	* For use by FileSystem classes.
	*/
	int getPrefixLength() {
	return prefixLength;
	}

	/**
	* The system-dependent default name-separator character. This field is
	* initialized to contain the first character of the value of the system
	* property {@code file.separator}. On UNIX systems the value of this
	* field is {@code '/'}; on Microsoft Windows systems it is {@code '\\'}.
	*
	* @see java.lang.System#getProperty(java.lang.String)
	*/
	public static final char separatorChar = fs.getSeparator();

	/**
	* The system-dependent default name-separator character, represented as a
	* string for convenience. This string contains a single character, namely
	* {@link #separatorChar}.
	*/
	public static final String separator = "" + separatorChar;

	/**
	* The system-dependent path-separator character. This field is
	* initialized to contain the first character of the value of the system
	* property {@code path.separator}. This character is used to
	* separate filenames in a sequence of files given as a <em>path list</em>.
	* On UNIX systems, this character is {@code ':'}; on Microsoft Windows systems it
	* is {@code ';'}.
	*
	* @see java.lang.System#getProperty(java.lang.String)
	*/
	public static final char pathSeparatorChar = fs.getPathSeparator();

	/**
	* The system-dependent path-separator character, represented as a string
	* for convenience. This string contains a single character, namely
	* {@link #pathSeparatorChar}.
	*/
	public static final String pathSeparator = "" + pathSeparatorChar;


	/* -- Constructors -- */

	/**
	* Internal constructor for already-normalized pathname strings.
	*/
	private File(String pathname, int prefixLength) {
	this.path = pathname;
	this.prefixLength = prefixLength;
	}

	/**
	* Internal constructor for already-normalized pathname strings.
	* The parameter order is used to disambiguate this method from the
	* public(File, String) constructor.
	*/
	private File(String child, File parent) {
	assert parent.path != null;
	assert (!parent.path.isEmpty());
	this.path = fs.resolve(parent.path, child);
	this.prefixLength = parent.prefixLength;
	}

	/**
	* Creates a new {@code File} instance by converting the given
	* pathname string into an abstract pathname. If the given string is
	* the empty string, then the result is the empty abstract pathname.
	*
	* @param pathname A pathname string
	* @throws NullPointerException
	* If the {@code pathname} argument is {@code null}
	*/
	public File(String pathname) {
	if (pathname == null) {
	throw new NullPointerException();
	}
	this.path = fs.normalize(pathname);
	this.prefixLength = fs.prefixLength(this.path);
	}

	/* Note: The two-argument File constructors do not interpret an empty
	parent abstract pathname as the current user directory. An empty parent
	instead causes the child to be resolved against the system-dependent
	directory defined by the FileSystem.getDefaultParent method. On Unix
	this default is "/", while on Microsoft Windows it is "\\". This is required for
	compatibility with the original behavior of this class. */

	/**
	* Creates a new {@code File} instance from a parent pathname string
	* and a child pathname string.
	*
	* <p> If {@code parent} is {@code null} then the new
	* {@code File} instance is created as if by invoking the
	* single-argument {@code File} constructor on the given
	* {@code child} pathname string.
	*
	* <p> Otherwise the {@code parent} pathname string is taken to denote
	* a directory, and the {@code child} pathname string is taken to
	* denote either a directory or a file. If the {@code child} pathname
	* string is absolute then it is converted into a relative pathname in a
	* system-dependent way. If {@code parent} is the empty string then
	* the new {@code File} instance is created by converting
	* {@code child} into an abstract pathname and resolving the result
	* against a system-dependent default directory. Otherwise each pathname
	* string is converted into an abstract pathname and the child abstract
	* pathname is resolved against the parent.
	*
	* @param parent The parent pathname string
	* @param child The child pathname string
	* @throws NullPointerException
	* If {@code child} is {@code null}
	*/
	public File(String parent, String child) {
	if (child == null) {
	throw new NullPointerException();
	}
	if (parent != null) {
	if (parent.isEmpty()) {
	this.path = fs.resolve(fs.getDefaultParent(),
	fs.normalize(child));
	} else {
	this.path = fs.resolve(fs.normalize(parent),
	fs.normalize(child));
	}
	} else {
	this.path = fs.normalize(child);
	}
	this.prefixLength = fs.prefixLength(this.path);
	}

	/**
	* Creates a new {@code File} instance from a parent abstract
	* pathname and a child pathname string.
	*
	* <p> If {@code parent} is {@code null} then the new
	* {@code File} instance is created as if by invoking the
	* single-argument {@code File} constructor on the given
	* {@code child} pathname string.
	*
	* <p> Otherwise the {@code parent} abstract pathname is taken to
	* denote a directory, and the {@code child} pathname string is taken
	* to denote either a directory or a file. If the {@code child}
	* pathname string is absolute then it is converted into a relative
	* pathname in a system-dependent way. If {@code parent} is the empty
	* abstract pathname then the new {@code File} instance is created by
	* converting {@code child} into an abstract pathname and resolving
	* the result against a system-dependent default directory. Otherwise each
	* pathname string is converted into an abstract pathname and the child
	* abstract pathname is resolved against the parent.
	*
	* @param parent The parent abstract pathname
	* @param child The child pathname string
	* @throws NullPointerException
	* If {@code child} is {@code null}
	*/
	public File(File parent, String child) {
	if (child == null) {
	throw new NullPointerException();
	}
	if (parent != null) {
	if (parent.path.isEmpty()) {
	this.path = fs.resolve(fs.getDefaultParent(),
	fs.normalize(child));
	} else {
	this.path = fs.resolve(parent.path,
	fs.normalize(child));
	}
	} else {
	this.path = fs.normalize(child);
	}
	this.prefixLength = fs.prefixLength(this.path);
	}

	/**
	* Creates a new {@code File} instance by converting the given
	* {@code file:} URI into an abstract pathname.
	*
	* <p> The exact form of a {@code file:} URI is system-dependent, hence
	* the transformation performed by this constructor is also
	* system-dependent.
	*
	* <p> For a given abstract pathname <i>f</i> it is guaranteed that
	*
	* <blockquote><code>
	* new File(</code><i> f</i><code>.{@link #toURI()
	* toURI}()).equals(</code><i> f</i><code>.{@link #getAbsoluteFile() getAbsoluteFile}())
	* </code></blockquote>
	*
	* so long as the original abstract pathname, the URI, and the new abstract
	* pathname are all created in (possibly different invocations of) the same
	* Java virtual machine. This relationship typically does not hold,
	* however, when a {@code file:} URI that is created in a virtual machine
	* on one operating system is converted into an abstract pathname in a
	* virtual machine on a different operating system.
	*
	* @param uri
	* An absolute, hierarchical URI with a scheme equal to
	* {@code "file"}, a non-empty path component, and undefined
	* authority, query, and fragment components
	*
	* @throws NullPointerException
	* If {@code uri} is {@code null}
	*
	* @throws IllegalArgumentException
	* If the preconditions on the parameter do not hold
	*
	* @see #toURI()
	* @see java.net.URI
	* @since 1.4
	*/
	public File(URI uri) {

	// Check our many preconditions
	if (!uri.isAbsolute())
	throw new IllegalArgumentException("URI is not absolute");
	if (uri.isOpaque())
	throw new IllegalArgumentException("URI is not hierarchical");
	String scheme = uri.getScheme();
	if ((scheme == null) \|\| !scheme.equalsIgnoreCase("file"))
	throw new IllegalArgumentException("URI scheme is not \"file\"");
	if (uri.getRawAuthority() != null)
	throw new IllegalArgumentException("URI has an authority component");
	if (uri.getRawFragment() != null)
	throw new IllegalArgumentException("URI has a fragment component");
	if (uri.getRawQuery() != null)
	throw new IllegalArgumentException("URI has a query component");
	String p = uri.getPath();
	if (p.isEmpty())
	throw new IllegalArgumentException("URI path component is empty");

	// Okay, now initialize
	p = fs.fromURIPath(p);
	if (File.separatorChar != '/')
	p = p.replace('/', File.separatorChar);
	this.path = fs.normalize(p);
	this.prefixLength = fs.prefixLength(this.path);
	}


	/* -- Path-component accessors -- */

	/**
	* Returns the name of the file or directory denoted by this abstract
	* pathname. This is just the last name in the pathname's name
	* sequence. If the pathname's name sequence is empty, then the empty
	* string is returned.
	*
	* @return The name of the file or directory denoted by this abstract
	* pathname, or the empty string if this pathname's name sequence
	* is empty
	*/
	public String getName() {
	int index = path.lastIndexOf(separatorChar);
	if (index < prefixLength) return path.substring(prefixLength);
	return path.substring(index + 1);
	}

	/**
	* Returns the pathname string of this abstract pathname's parent, or
	* {@code null} if this pathname does not name a parent directory.
	*
	* <p> The <em>parent</em> of an abstract pathname consists of the
	* pathname's prefix, if any, and each name in the pathname's name
	* sequence except for the last. If the name sequence is empty then
	* the pathname does not name a parent directory.
	*
	* @return The pathname string of the parent directory named by this
	* abstract pathname, or {@code null} if this pathname
	* does not name a parent
	*/
	public String getParent() {
	int index = path.lastIndexOf(separatorChar);
	if (index < prefixLength) {
	if ((prefixLength > 0) && (path.length() > prefixLength))
	return path.substring(0, prefixLength);
	return null;
	}
	return path.substring(0, index);
	}

	/**
	* Returns the abstract pathname of this abstract pathname's parent,
	* or {@code null} if this pathname does not name a parent
	* directory.
	*
	* <p> The <em>parent</em> of an abstract pathname consists of the
	* pathname's prefix, if any, and each name in the pathname's name
	* sequence except for the last. If the name sequence is empty then
	* the pathname does not name a parent directory.
	*
	* @return The abstract pathname of the parent directory named by this
	* abstract pathname, or {@code null} if this pathname
	* does not name a parent
	*
	* @since 1.2
	*/
	public File getParentFile() {
	String p = this.getParent();
	if (p == null) return null;
	if (getClass() != File.class) {
	p = fs.normalize(p);
	}
	return new File(p, this.prefixLength);
	}

	/**
	* Converts this abstract pathname into a pathname string. The resulting
	* string uses the {@link #separator default name-separator character} to
	* separate the names in the name sequence.
	*
	* @return The string form of this abstract pathname
	*/
	public String getPath() {
	return path;
	}


	/* -- Path operations -- */

	/**
	* Tests whether this abstract pathname is absolute. The definition of
	* absolute pathname is system dependent. On UNIX systems, a pathname is
	* absolute if its prefix is {@code "/"}. On Microsoft Windows systems, a
	* pathname is absolute if its prefix is a drive specifier followed by
	* {@code "\\"}, or if its prefix is {@code "\\\\"}.
	*
	* @return {@code true} if this abstract pathname is absolute,
	* {@code false} otherwise
	*/
	public boolean isAbsolute() {
	return fs.isAbsolute(this);
	}

	/**
	* Returns the absolute pathname string of this abstract pathname.
	*
	* <p> If this abstract pathname is already absolute, then the pathname
	* string is simply returned as if by the {@link #getPath}
	* method. If this abstract pathname is the empty abstract pathname then
	* the pathname string of the current user directory, which is named by the
	* system property {@code user.dir}, is returned. Otherwise this
	* pathname is resolved in a system-dependent way. On UNIX systems, a
	* relative pathname is made absolute by resolving it against the current
	* user directory. On Microsoft Windows systems, a relative pathname is made absolute
	* by resolving it against the current directory of the drive named by the
	* pathname, if any; if not, it is resolved against the current user
	* directory.
	*
	* @return The absolute pathname string denoting the same file or
	* directory as this abstract pathname
	*
	* @throws SecurityException
	* If a required system property value cannot be accessed.
	*
	* @see java.io.File#isAbsolute()
	*/
	public String getAbsolutePath() {
	return fs.resolve(this);
	}

	/**
	* Returns the absolute form of this abstract pathname. Equivalent to
	* <code>new File(this.{@link #getAbsolutePath})</code>.
	*
	* @return The absolute abstract pathname denoting the same file or
	* directory as this abstract pathname
	*
	* @throws SecurityException
	* If a required system property value cannot be accessed.
	*
	* @since 1.2
	*/
	public File getAbsoluteFile() {
	String absPath = getAbsolutePath();
	if (getClass() != File.class) {
	absPath = fs.normalize(absPath);
	}
	return new File(absPath, fs.prefixLength(absPath));
	}

	/**
	* Returns the canonical pathname string of this abstract pathname.
	*
	* <p> A canonical pathname is both absolute and unique. The precise
	* definition of canonical form is system-dependent. This method first
	* converts this pathname to absolute form if necessary, as if by invoking the
	* {@link #getAbsolutePath} method, and then maps it to its unique form in a
	* system-dependent way. This typically involves removing redundant names
	* such as {@code "."} and {@code ".."} from the pathname, resolving
	* symbolic links (on UNIX platforms), and converting drive letters to a
	* standard case (on Microsoft Windows platforms).
	*
	* <p> Every pathname that denotes an existing file or directory has a
	* unique canonical form. Every pathname that denotes a nonexistent file
	* or directory also has a unique canonical form. The canonical form of
	* the pathname of a nonexistent file or directory may be different from
	* the canonical form of the same pathname after the file or directory is
	* created. Similarly, the canonical form of the pathname of an existing
	* file or directory may be different from the canonical form of the same
	* pathname after the file or directory is deleted.
	*
	* @return The canonical pathname string denoting the same file or
	* directory as this abstract pathname
	*
	* @throws IOException
	* If an I/O error occurs, which is possible because the
	* construction of the canonical pathname may require
	* filesystem queries
	*
	* @throws SecurityException
	* If a required system property value cannot be accessed, or
	* if a security manager exists and its {@link
	* java.lang.SecurityManager#checkRead} method denies
	* read access to the file
	*
	* @since 1.1
	* @see Path#toRealPath
	*/
	public String getCanonicalPath() throws IOException {
	if (isInvalid()) {
	throw new IOException("Invalid file path");
	}
	return fs.canonicalize(fs.resolve(this));
	}

	/**
	* Returns the canonical form of this abstract pathname. Equivalent to
	* <code>new File(this.{@link #getCanonicalPath})</code>.
	*
	* @return The canonical pathname string denoting the same file or
	* directory as this abstract pathname
	*
	* @throws IOException
	* If an I/O error occurs, which is possible because the
	* construction of the canonical pathname may require
	* filesystem queries
	*
	* @throws SecurityException
	* If a required system property value cannot be accessed, or
	* if a security manager exists and its {@link
	* java.lang.SecurityManager#checkRead} method denies
	* read access to the file
	*
	* @since 1.2
	* @see Path#toRealPath
	*/
	public File getCanonicalFile() throws IOException {
	String canonPath = getCanonicalPath();
	if (getClass() != File.class) {
	canonPath = fs.normalize(canonPath);
	}
	return new File(canonPath, fs.prefixLength(canonPath));
	}

	private static String slashify(String path, boolean isDirectory) {
	String p = path;
	if (File.separatorChar != '/')
	p = p.replace(File.separatorChar, '/');
	if (!p.startsWith("/"))
	p = "/" + p;
	if (!p.endsWith("/") && isDirectory)
	p = p + "/";
	return p;
	}

	/**
	* Converts this abstract pathname into a {@code file:} URL. The
	* exact form of the URL is system-dependent. If it can be determined that
	* the file denoted by this abstract pathname is a directory, then the
	* resulting URL will end with a slash.
	*
	* @return A URL object representing the equivalent file URL
	*
	* @throws MalformedURLException
	* If the path cannot be parsed as a URL
	*
	* @see #toURI()
	* @see java.net.URI
	* @see java.net.URI#toURL()
	* @see java.net.URL
	* @since 1.2
	*
	* @deprecated This method does not automatically escape characters that
	* are illegal in URLs. It is recommended that new code convert an
	* abstract pathname into a URL by first converting it into a URI, via the
	* {@link #toURI() toURI} method, and then converting the URI into a URL
	* via the {@link java.net.URI#toURL() URI.toURL} method.
	*/
	@Deprecated
	public URL toURL() throws MalformedURLException {
	if (isInvalid()) {
	throw new MalformedURLException("Invalid file path");
	}
	return new URL("file", "", slashify(getAbsolutePath(), isDirectory()));
	}

	/**
	* Constructs a {@code file:} URI that represents this abstract pathname.
	*
	* <p> The exact form of the URI is system-dependent. If it can be
	* determined that the file denoted by this abstract pathname is a
	* directory, then the resulting URI will end with a slash.
	*
	* <p> For a given abstract pathname <i>f</i>, it is guaranteed that
	*
	* <blockquote><code>
	* new {@link #File(java.net.URI) File}(</code><i> f</i><code>.toURI()).equals(
	* </code><i> f</i><code>.{@link #getAbsoluteFile() getAbsoluteFile}())
	* </code></blockquote>
	*
	* so long as the original abstract pathname, the URI, and the new abstract
	* pathname are all created in (possibly different invocations of) the same
	* Java virtual machine. Due to the system-dependent nature of abstract
	* pathnames, however, this relationship typically does not hold when a
	* {@code file:} URI that is created in a virtual machine on one operating
	* system is converted into an abstract pathname in a virtual machine on a
	* different operating system.
	*
	* <p> Note that when this abstract pathname represents a UNC pathname then
	* all components of the UNC (including the server name component) are encoded
	* in the {@code URI} path. The authority component is undefined, meaning
	* that it is represented as {@code null}. The {@link Path} class defines the
	* {@link Path#toUri toUri} method to encode the server name in the authority
	* component of the resulting {@code URI}. The {@link #toPath toPath} method
	* may be used to obtain a {@code Path} representing this abstract pathname.
	*
	* @return An absolute, hierarchical URI with a scheme equal to
	* {@code "file"}, a path representing this abstract pathname,
	* and undefined authority, query, and fragment components
	* @throws SecurityException If a required system property value cannot
	* be accessed.
	*
	* @see #File(java.net.URI)
	* @see java.net.URI
	* @see java.net.URI#toURL()
	* @since 1.4
	*/
	public URI toURI() {
	try {
	File f = getAbsoluteFile();
	String sp = slashify(f.getPath(), f.isDirectory());
	if (sp.startsWith("//"))
	sp = "//" + sp;
	return new URI("file", null, sp, null);
	} catch (URISyntaxException x) {
	throw new Error(x); // Can't happen
	}
	}


	/* -- Attribute accessors -- */

	/**
	* Tests whether the application can read the file denoted by this
	* abstract pathname. On some platforms it may be possible to start the
	* Java virtual machine with special privileges that allow it to read
	* files that are marked as unreadable. Consequently this method may return
	* {@code true} even though the file does not have read permissions.
	*
	* @return {@code true} if and only if the file specified by this
	* abstract pathname exists <em>and</em> can be read by the
	* application; {@code false} otherwise
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkRead(java.lang.String)}
	* method denies read access to the file
	*/
	public boolean canRead() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkRead(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.checkAccess(this, FileSystem.ACCESS_READ);
	}

	/**
	* Tests whether the application can modify the file denoted by this
	* abstract pathname. On some platforms it may be possible to start the
	* Java virtual machine with special privileges that allow it to modify
	* files that are marked read-only. Consequently this method may return
	* {@code true} even though the file is marked read-only.
	*
	* @return {@code true} if and only if the file system actually
	* contains a file denoted by this abstract pathname <em>and</em>
	* the application is allowed to write to the file;
	* {@code false} otherwise.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to the file
	*/
	public boolean canWrite() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkWrite(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.checkAccess(this, FileSystem.ACCESS_WRITE);
	}

	/**
	* Tests whether the file or directory denoted by this abstract pathname
	* exists.
	*
	* @return {@code true} if and only if the file or directory denoted
	* by this abstract pathname exists; {@code false} otherwise
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkRead(java.lang.String)}
	* method denies read access to the file or directory
	*/
	public boolean exists() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkRead(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.hasBooleanAttributes(this, FileSystem.BA_EXISTS);
	}

	/**
	* Tests whether the file denoted by this abstract pathname is a
	* directory.
	*
	* <p> Where it is required to distinguish an I/O exception from the case
	* that the file is not a directory, or where several attributes of the
	* same file are required at the same time, then the {@link
	* java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
	* Files.readAttributes} method may be used.
	*
	* @return {@code true} if and only if the file denoted by this
	* abstract pathname exists <em>and</em> is a directory;
	* {@code false} otherwise
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkRead(java.lang.String)}
	* method denies read access to the file
	*/
	public boolean isDirectory() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkRead(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.hasBooleanAttributes(this, FileSystem.BA_DIRECTORY);
	}

	/**
	* Tests whether the file denoted by this abstract pathname is a normal
	* file. A file is <em>normal</em> if it is not a directory and, in
	* addition, satisfies other system-dependent criteria. Any non-directory
	* file created by a Java application is guaranteed to be a normal file.
	*
	* <p> Where it is required to distinguish an I/O exception from the case
	* that the file is not a normal file, or where several attributes of the
	* same file are required at the same time, then the {@link
	* java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
	* Files.readAttributes} method may be used.
	*
	* @return {@code true} if and only if the file denoted by this
	* abstract pathname exists <em>and</em> is a normal file;
	* {@code false} otherwise
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkRead(java.lang.String)}
	* method denies read access to the file
	*/
	public boolean isFile() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkRead(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.hasBooleanAttributes(this, FileSystem.BA_REGULAR);
	}

	/**
	* Tests whether the file named by this abstract pathname is a hidden
	* file. The exact definition of <em>hidden</em> is system-dependent. On
	* UNIX systems, a file is considered to be hidden if its name begins with
	* a period character ({@code '.'}). On Microsoft Windows systems, a file is
	* considered to be hidden if it has been marked as such in the filesystem.
	*
	* @return {@code true} if and only if the file denoted by this
	* abstract pathname is hidden according to the conventions of the
	* underlying platform
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkRead(java.lang.String)}
	* method denies read access to the file
	*
	* @since 1.2
	*/
	public boolean isHidden() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkRead(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.hasBooleanAttributes(this, FileSystem.BA_HIDDEN);
	}

	/**
	* Returns the time that the file denoted by this abstract pathname was
	* last modified.
	*
	* @apiNote
	* While the unit of time of the return value is milliseconds, the
	* granularity of the value depends on the underlying file system and may
	* be larger. For example, some file systems use time stamps in units of
	* seconds.
	*
	* <p> Where it is required to distinguish an I/O exception from the case
	* where {@code 0L} is returned, or where several attributes of the
	* same file are required at the same time, or where the time of last
	* access or the creation time are required, then the {@link
	* java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
	* Files.readAttributes} method may be used. If however only the
	* time of last modification is required, then the
	* {@link java.nio.file.Files#getLastModifiedTime(Path,LinkOption[])
	* Files.getLastModifiedTime} method may be used instead.
	*
	* @return A {@code long} value representing the time the file was
	* last modified, measured in milliseconds since the epoch
	* (00:00:00 GMT, January 1, 1970), or {@code 0L} if the
	* file does not exist or if an I/O error occurs. The value may
	* be negative indicating the number of milliseconds before the
	* epoch
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkRead(java.lang.String)}
	* method denies read access to the file
	*/
	public long lastModified() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkRead(path);
	}
	if (isInvalid()) {
	return 0L;
	}
	return fs.getLastModifiedTime(this);
	}

	/**
	* Returns the length of the file denoted by this abstract pathname.
	* The return value is unspecified if this pathname denotes a directory.
	*
	* <p> Where it is required to distinguish an I/O exception from the case
	* that {@code 0L} is returned, or where several attributes of the same file
	* are required at the same time, then the {@link
	* java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
	* Files.readAttributes} method may be used.
	*
	* @return The length, in bytes, of the file denoted by this abstract
	* pathname, or {@code 0L} if the file does not exist. Some
	* operating systems may return {@code 0L} for pathnames
	* denoting system-dependent entities such as devices or pipes.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkRead(java.lang.String)}
	* method denies read access to the file
	*/
	public long length() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkRead(path);
	}
	if (isInvalid()) {
	return 0L;
	}
	return fs.getLength(this);
	}


	/* -- File operations -- */

	/**
	* Atomically creates a new, empty file named by this abstract pathname if
	* and only if a file with this name does not yet exist. The check for the
	* existence of the file and the creation of the file if it does not exist
	* are a single operation that is atomic with respect to all other
	* filesystem activities that might affect the file.
	* <P>
	* Note: this method should <i>not</i> be used for file-locking, as
	* the resulting protocol cannot be made to work reliably. The
	* {@link java.nio.channels.FileLock FileLock}
	* facility should be used instead.
	*
	* @return {@code true} if the named file does not exist and was
	* successfully created; {@code false} if the named file
	* already exists
	*
	* @throws IOException
	* If an I/O error occurred
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to the file
	*
	* @since 1.2
	*/
	public boolean createNewFile() throws IOException {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) security.checkWrite(path);
	if (isInvalid()) {
	throw new IOException("Invalid file path");
	}
	return fs.createFileExclusively(path);
	}

	/**
	* Deletes the file or directory denoted by this abstract pathname. If
	* this pathname denotes a directory, then the directory must be empty in
	* order to be deleted.
	*
	* <p> Note that the {@link java.nio.file.Files} class defines the {@link
	* java.nio.file.Files#delete(Path) delete} method to throw an {@link IOException}
	* when a file cannot be deleted. This is useful for error reporting and to
	* diagnose why a file cannot be deleted.
	*
	* @return {@code true} if and only if the file or directory is
	* successfully deleted; {@code false} otherwise
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkDelete} method denies
	* delete access to the file
	*/
	public boolean delete() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkDelete(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.delete(this);
	}

	/**
	* Requests that the file or directory denoted by this abstract
	* pathname be deleted when the virtual machine terminates.
	* Files (or directories) are deleted in the reverse order that
	* they are registered. Invoking this method to delete a file or
	* directory that is already registered for deletion has no effect.
	* Deletion will be attempted only for normal termination of the
	* virtual machine, as defined by the Java Language Specification.
	*
	* <p> Once deletion has been requested, it is not possible to cancel the
	* request. This method should therefore be used with care.
	*
	* <P>
	* Note: this method should <i>not</i> be used for file-locking, as
	* the resulting protocol cannot be made to work reliably. The
	* {@link java.nio.channels.FileLock FileLock}
	* facility should be used instead.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkDelete} method denies
	* delete access to the file
	*
	* @see #delete
	*
	* @since 1.2
	*/
	public void deleteOnExit() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkDelete(path);
	}
	if (isInvalid()) {
	return;
	}
	DeleteOnExitHook.add(path);
	}

	/**
	* Returns an array of strings naming the files and directories in the
	* directory denoted by this abstract pathname.
	*
	* <p> If this abstract pathname does not denote a directory, then this
	* method returns {@code null}. Otherwise an array of strings is
	* returned, one for each file or directory in the directory. Names
	* denoting the directory itself and the directory's parent directory are
	* not included in the result. Each string is a file name rather than a
	* complete path.
	*
	* <p> There is no guarantee that the name strings in the resulting array
	* will appear in any specific order; they are not, in particular,
	* guaranteed to appear in alphabetical order.
	*
	* <p> Note that the {@link java.nio.file.Files} class defines the {@link
	* java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method to
	* open a directory and iterate over the names of the files in the directory.
	* This may use less resources when working with very large directories, and
	* may be more responsive when working with remote directories.
	*
	* @return An array of strings naming the files and directories in the
	* directory denoted by this abstract pathname. The array will be
	* empty if the directory is empty. Returns {@code null} if
	* this abstract pathname does not denote a directory, or if an
	* I/O error occurs.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* SecurityManager#checkRead(String)} method denies read access to
	* the directory
	*/
	public String[] list() {
	return normalizedList();
	}

	/**
	* Returns an array of strings naming the files and directories in the
	* directory denoted by this abstract pathname. The strings are
	* ensured to represent normalized paths.
	*
	* @return An array of strings naming the files and directories in the
	* directory denoted by this abstract pathname. The array will be
	* empty if the directory is empty. Returns {@code null} if
	* this abstract pathname does not denote a directory, or if an
	* I/O error occurs.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* SecurityManager#checkRead(String)} method denies read access to
	* the directory
	*/
	private final String[] normalizedList() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkRead(path);
	}
	if (isInvalid()) {
	return null;
	}
	String[] s = fs.list(this);
	if (s != null && getClass() != File.class) {
	String[] normalized = new String[s.length];
	for (int i = 0; i < s.length; i++) {
	normalized[i] = fs.normalize(s[i]);
	}
	s = normalized;
	}
	return s;
	}

	/**
	* Returns an array of strings naming the files and directories in the
	* directory denoted by this abstract pathname that satisfy the specified
	* filter. The behavior of this method is the same as that of the
	* {@link #list()} method, except that the strings in the returned array
	* must satisfy the filter. If the given {@code filter} is {@code null}
	* then all names are accepted. Otherwise, a name satisfies the filter if
	* and only if the value {@code true} results when the {@link
	* FilenameFilter#accept FilenameFilter.accept(File, String)} method
	* of the filter is invoked on this abstract pathname and the name of a
	* file or directory in the directory that it denotes.
	*
	* @param filter
	* A filename filter
	*
	* @return An array of strings naming the files and directories in the
	* directory denoted by this abstract pathname that were accepted
	* by the given {@code filter}. The array will be empty if the
	* directory is empty or if no names were accepted by the filter.
	* Returns {@code null} if this abstract pathname does not denote
	* a directory, or if an I/O error occurs.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* SecurityManager#checkRead(String)} method denies read access to
	* the directory
	*
	* @see java.nio.file.Files#newDirectoryStream(Path,String)
	*/
	public String[] list(FilenameFilter filter) {
	String names[] = normalizedList();
	if ((names == null) \|\| (filter == null)) {
	return names;
	}
	List<String> v = new ArrayList<>();
	for (int i = 0 ; i < names.length ; i++) {
	if (filter.accept(this, names[i])) {
	v.add(names[i]);
	}
	}
	return v.toArray(new String[v.size()]);
	}

	/**
	* Returns an array of abstract pathnames denoting the files in the
	* directory denoted by this abstract pathname.
	*
	* <p> If this abstract pathname does not denote a directory, then this
	* method returns {@code null}. Otherwise an array of {@code File} objects
	* is returned, one for each file or directory in the directory. Pathnames
	* denoting the directory itself and the directory's parent directory are
	* not included in the result. Each resulting abstract pathname is
	* constructed from this abstract pathname using the {@link #File(File,
	* String) File(File, String)} constructor. Therefore if this
	* pathname is absolute then each resulting pathname is absolute; if this
	* pathname is relative then each resulting pathname will be relative to
	* the same directory.
	*
	* <p> There is no guarantee that the name strings in the resulting array
	* will appear in any specific order; they are not, in particular,
	* guaranteed to appear in alphabetical order.
	*
	* <p> Note that the {@link java.nio.file.Files} class defines the {@link
	* java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method
	* to open a directory and iterate over the names of the files in the
	* directory. This may use less resources when working with very large
	* directories.
	*
	* @return An array of abstract pathnames denoting the files and
	* directories in the directory denoted by this abstract pathname.
	* The array will be empty if the directory is empty. Returns
	* {@code null} if this abstract pathname does not denote a
	* directory, or if an I/O error occurs.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* SecurityManager#checkRead(String)} method denies read access to
	* the directory
	*
	* @since 1.2
	*/
	public File[] listFiles() {
	String[] ss = normalizedList();
	if (ss == null) return null;
	int n = ss.length;
	File[] fs = new File[n];
	for (int i = 0; i < n; i++) {
	fs[i] = new File(ss[i], this);
	}
	return fs;
	}

	/**
	* Returns an array of abstract pathnames denoting the files and
	* directories in the directory denoted by this abstract pathname that
	* satisfy the specified filter. The behavior of this method is the same
	* as that of the {@link #listFiles()} method, except that the pathnames in
	* the returned array must satisfy the filter. If the given {@code filter}
	* is {@code null} then all pathnames are accepted. Otherwise, a pathname
	* satisfies the filter if and only if the value {@code true} results when
	* the {@link FilenameFilter#accept
	* FilenameFilter.accept(File, String)} method of the filter is
	* invoked on this abstract pathname and the name of a file or directory in
	* the directory that it denotes.
	*
	* @param filter
	* A filename filter
	*
	* @return An array of abstract pathnames denoting the files and
	* directories in the directory denoted by this abstract pathname.
	* The array will be empty if the directory is empty. Returns
	* {@code null} if this abstract pathname does not denote a
	* directory, or if an I/O error occurs.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* SecurityManager#checkRead(String)} method denies read access to
	* the directory
	*
	* @since 1.2
	* @see java.nio.file.Files#newDirectoryStream(Path,String)
	*/
	public File[] listFiles(FilenameFilter filter) {
	String ss[] = normalizedList();
	if (ss == null) return null;
	ArrayList<File> files = new ArrayList<>();
	for (String s : ss)
	if ((filter == null) \|\| filter.accept(this, s))
	files.add(new File(s, this));
	return files.toArray(new File[files.size()]);
	}

	/**
	* Returns an array of abstract pathnames denoting the files and
	* directories in the directory denoted by this abstract pathname that
	* satisfy the specified filter. The behavior of this method is the same
	* as that of the {@link #listFiles()} method, except that the pathnames in
	* the returned array must satisfy the filter. If the given {@code filter}
	* is {@code null} then all pathnames are accepted. Otherwise, a pathname
	* satisfies the filter if and only if the value {@code true} results when
	* the {@link FileFilter#accept FileFilter.accept(File)} method of the
	* filter is invoked on the pathname.
	*
	* @param filter
	* A file filter
	*
	* @return An array of abstract pathnames denoting the files and
	* directories in the directory denoted by this abstract pathname.
	* The array will be empty if the directory is empty. Returns
	* {@code null} if this abstract pathname does not denote a
	* directory, or if an I/O error occurs.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* SecurityManager#checkRead(String)} method denies read access to
	* the directory
	*
	* @since 1.2
	* @see java.nio.file.Files#newDirectoryStream(Path,java.nio.file.DirectoryStream.Filter)
	*/
	public File[] listFiles(FileFilter filter) {
	String ss[] = normalizedList();
	if (ss == null) return null;
	ArrayList<File> files = new ArrayList<>();
	for (String s : ss) {
	File f = new File(s, this);
	if ((filter == null) \|\| filter.accept(f))
	files.add(f);
	}
	return files.toArray(new File[files.size()]);
	}

	/**
	* Creates the directory named by this abstract pathname.
	*
	* @return {@code true} if and only if the directory was
	* created; {@code false} otherwise
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method does not permit the named directory to be created
	*/
	public boolean mkdir() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkWrite(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.createDirectory(this);
	}

	/**
	* Creates the directory named by this abstract pathname, including any
	* necessary but nonexistent parent directories. Note that if this
	* operation fails it may have succeeded in creating some of the necessary
	* parent directories.
	*
	* @return {@code true} if and only if the directory was created,
	* along with all necessary parent directories; {@code false}
	* otherwise
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkRead(java.lang.String)}
	* method does not permit verification of the existence of the
	* named directory and all necessary parent directories; or if
	* the {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method does not permit the named directory and all necessary
	* parent directories to be created
	*/
	public boolean mkdirs() {
	if (exists()) {
	return false;
	}
	if (mkdir()) {
	return true;
	}
	File canonFile = null;
	try {
	canonFile = getCanonicalFile();
	} catch (IOException e) {
	return false;
	}

	File parent = canonFile.getParentFile();
	return (parent != null && (parent.mkdirs() \|\| parent.exists()) &&
	canonFile.mkdir());
	}

	/**
	* Renames the file denoted by this abstract pathname.
	*
	* <p> Many aspects of the behavior of this method are inherently
	* platform-dependent: The rename operation might not be able to move a
	* file from one filesystem to another, it might not be atomic, and it
	* might not succeed if a file with the destination abstract pathname
	* already exists. The return value should always be checked to make sure
	* that the rename operation was successful. As instances of {@code File}
	* are immutable, this File object is not changed to name the destination
	* file or directory.
	*
	* <p> Note that the {@link java.nio.file.Files} class defines the {@link
	* java.nio.file.Files#move move} method to move or rename a file in a
	* platform independent manner.
	*
	* @param dest The new abstract pathname for the named file
	*
	* @return {@code true} if and only if the renaming succeeded;
	* {@code false} otherwise
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to either the old or new pathnames
	*
	* @throws NullPointerException
	* If parameter {@code dest} is {@code null}
	*/
	public boolean renameTo(File dest) {
	if (dest == null) {
	throw new NullPointerException();
	}
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkWrite(path);
	security.checkWrite(dest.path);
	}
	if (this.isInvalid() \|\| dest.isInvalid()) {
	return false;
	}
	return fs.rename(this, dest);
	}

	/**
	* Sets the last-modified time of the file or directory named by this
	* abstract pathname.
	*
	* <p> All platforms support file-modification times to the nearest second,
	* but some provide more precision. The argument will be truncated to fit
	* the supported precision. If the operation succeeds and no intervening
	* operations on the file take place, then the next invocation of the
	* {@link #lastModified} method will return the (possibly
	* truncated) {@code time} argument that was passed to this method.
	*
	* @param time The new last-modified time, measured in milliseconds since
	* the epoch (00:00:00 GMT, January 1, 1970)
	*
	* @return {@code true} if and only if the operation succeeded;
	* {@code false} otherwise
	*
	* @throws IllegalArgumentException If the argument is negative
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to the named file
	*
	* @since 1.2
	*/
	public boolean setLastModified(long time) {
	if (time < 0) throw new IllegalArgumentException("Negative time");
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkWrite(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.setLastModifiedTime(this, time);
	}

	/**
	* Marks the file or directory named by this abstract pathname so that
	* only read operations are allowed. After invoking this method the file
	* or directory will not change until it is either deleted or marked
	* to allow write access. On some platforms it may be possible to start the
	* Java virtual machine with special privileges that allow it to modify
	* files that are marked read-only. Whether or not a read-only file or
	* directory may be deleted depends upon the underlying system.
	*
	* @return {@code true} if and only if the operation succeeded;
	* {@code false} otherwise
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to the named file
	*
	* @since 1.2
	*/
	public boolean setReadOnly() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkWrite(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.setReadOnly(this);
	}

	/**
	* Sets the owner's or everybody's write permission for this abstract
	* pathname. On some platforms it may be possible to start the Java virtual
	* machine with special privileges that allow it to modify files that
	* disallow write operations.
	*
	* <p> The {@link java.nio.file.Files} class defines methods that operate on
	* file attributes including file permissions. This may be used when finer
	* manipulation of file permissions is required.
	*
	* @param writable
	* If {@code true}, sets the access permission to allow write
	* operations; if {@code false} to disallow write operations
	*
	* @param ownerOnly
	* If {@code true}, the write permission applies only to the
	* owner's write permission; otherwise, it applies to everybody. If
	* the underlying file system can not distinguish the owner's write
	* permission from that of others, then the permission will apply to
	* everybody, regardless of this value.
	*
	* @return {@code true} if and only if the operation succeeded. The
	* operation will fail if the user does not have permission to change
	* the access permissions of this abstract pathname.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to the named file
	*
	* @since 1.6
	*/
	public boolean setWritable(boolean writable, boolean ownerOnly) {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkWrite(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.setPermission(this, FileSystem.ACCESS_WRITE, writable, ownerOnly);
	}

	/**
	* A convenience method to set the owner's write permission for this abstract
	* pathname. On some platforms it may be possible to start the Java virtual
	* machine with special privileges that allow it to modify files that
	* disallow write operations.
	*
	* <p> An invocation of this method of the form {@code file.setWritable(arg)}
	* behaves in exactly the same way as the invocation
	*
	* <pre>{@code
	* file.setWritable(arg, true)
	* }</pre>
	*
	* @param writable
	* If {@code true}, sets the access permission to allow write
	* operations; if {@code false} to disallow write operations
	*
	* @return {@code true} if and only if the operation succeeded. The
	* operation will fail if the user does not have permission to
	* change the access permissions of this abstract pathname.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to the file
	*
	* @since 1.6
	*/
	public boolean setWritable(boolean writable) {
	return setWritable(writable, true);
	}

	/**
	* Sets the owner's or everybody's read permission for this abstract
	* pathname. On some platforms it may be possible to start the Java virtual
	* machine with special privileges that allow it to read files that are
	* marked as unreadable.
	*
	* <p> The {@link java.nio.file.Files} class defines methods that operate on
	* file attributes including file permissions. This may be used when finer
	* manipulation of file permissions is required.
	*
	* @param readable
	* If {@code true}, sets the access permission to allow read
	* operations; if {@code false} to disallow read operations
	*
	* @param ownerOnly
	* If {@code true}, the read permission applies only to the
	* owner's read permission; otherwise, it applies to everybody. If
	* the underlying file system can not distinguish the owner's read
	* permission from that of others, then the permission will apply to
	* everybody, regardless of this value.
	*
	* @return {@code true} if and only if the operation succeeded. The
	* operation will fail if the user does not have permission to
	* change the access permissions of this abstract pathname. If
	* {@code readable} is {@code false} and the underlying
	* file system does not implement a read permission, then the
	* operation will fail.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to the file
	*
	* @since 1.6
	*/
	public boolean setReadable(boolean readable, boolean ownerOnly) {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkWrite(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.setPermission(this, FileSystem.ACCESS_READ, readable, ownerOnly);
	}

	/**
	* A convenience method to set the owner's read permission for this abstract
	* pathname. On some platforms it may be possible to start the Java virtual
	* machine with special privileges that allow it to read files that are
	* marked as unreadable.
	*
	* <p>An invocation of this method of the form {@code file.setReadable(arg)}
	* behaves in exactly the same way as the invocation
	*
	* <pre>{@code
	* file.setReadable(arg, true)
	* }</pre>
	*
	* @param readable
	* If {@code true}, sets the access permission to allow read
	* operations; if {@code false} to disallow read operations
	*
	* @return {@code true} if and only if the operation succeeded. The
	* operation will fail if the user does not have permission to
	* change the access permissions of this abstract pathname. If
	* {@code readable} is {@code false} and the underlying
	* file system does not implement a read permission, then the
	* operation will fail.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to the file
	*
	* @since 1.6
	*/
	public boolean setReadable(boolean readable) {
	return setReadable(readable, true);
	}

	/**
	* Sets the owner's or everybody's execute permission for this abstract
	* pathname. On some platforms it may be possible to start the Java virtual
	* machine with special privileges that allow it to execute files that are
	* not marked executable.
	*
	* <p> The {@link java.nio.file.Files} class defines methods that operate on
	* file attributes including file permissions. This may be used when finer
	* manipulation of file permissions is required.
	*
	* @param executable
	* If {@code true}, sets the access permission to allow execute
	* operations; if {@code false} to disallow execute operations
	*
	* @param ownerOnly
	* If {@code true}, the execute permission applies only to the
	* owner's execute permission; otherwise, it applies to everybody.
	* If the underlying file system can not distinguish the owner's
	* execute permission from that of others, then the permission will
	* apply to everybody, regardless of this value.
	*
	* @return {@code true} if and only if the operation succeeded. The
	* operation will fail if the user does not have permission to
	* change the access permissions of this abstract pathname. If
	* {@code executable} is {@code false} and the underlying
	* file system does not implement an execute permission, then the
	* operation will fail.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to the file
	*
	* @since 1.6
	*/
	public boolean setExecutable(boolean executable, boolean ownerOnly) {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkWrite(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.setPermission(this, FileSystem.ACCESS_EXECUTE, executable, ownerOnly);
	}

	/**
	* A convenience method to set the owner's execute permission for this
	* abstract pathname. On some platforms it may be possible to start the Java
	* virtual machine with special privileges that allow it to execute files
	* that are not marked executable.
	*
	* <p>An invocation of this method of the form {@code file.setExcutable(arg)}
	* behaves in exactly the same way as the invocation
	*
	* <pre>{@code
	* file.setExecutable(arg, true)
	* }</pre>
	*
	* @param executable
	* If {@code true}, sets the access permission to allow execute
	* operations; if {@code false} to disallow execute operations
	*
	* @return {@code true} if and only if the operation succeeded. The
	* operation will fail if the user does not have permission to
	* change the access permissions of this abstract pathname. If
	* {@code executable} is {@code false} and the underlying
	* file system does not implement an execute permission, then the
	* operation will fail.
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method denies write access to the file
	*
	* @since 1.6
	*/
	public boolean setExecutable(boolean executable) {
	return setExecutable(executable, true);
	}

	/**
	* Tests whether the application can execute the file denoted by this
	* abstract pathname. On some platforms it may be possible to start the
	* Java virtual machine with special privileges that allow it to execute
	* files that are not marked executable. Consequently this method may return
	* {@code true} even though the file does not have execute permissions.
	*
	* @return {@code true} if and only if the abstract pathname exists
	* <em>and</em> the application is allowed to execute the file
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkExec(java.lang.String)}
	* method denies execute access to the file
	*
	* @since 1.6
	*/
	public boolean canExecute() {
	@SuppressWarnings("removal")
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkExec(path);
	}
	if (isInvalid()) {
	return false;
	}
	return fs.checkAccess(this, FileSystem.ACCESS_EXECUTE);
	}


	/* -- Filesystem interface -- */

	/**
	* List the available filesystem roots.
	*
	* <p> A particular Java platform may support zero or more
	* hierarchically-organized file systems. Each file system has a
	* {@code root} directory from which all other files in that file system
	* can be reached. Windows platforms, for example, have a root directory
	* for each active drive; UNIX platforms have a single root directory,
	* namely {@code "/"}. The set of available filesystem roots is affected
	* by various system-level operations such as the insertion or ejection of
	* removable media and the disconnecting or unmounting of physical or
	* virtual disk drives.
	*
	* <p> This method returns an array of {@code File} objects that denote the
	* root directories of the available filesystem roots. It is guaranteed
	* that the canonical pathname of any file physically present on the local
	* machine will begin with one of the roots returned by this method.
	*
	* <p> The canonical pathname of a file that resides on some other machine
	* and is accessed via a remote-filesystem protocol such as SMB or NFS may
	* or may not begin with one of the roots returned by this method. If the
	* pathname of a remote file is syntactically indistinguishable from the
	* pathname of a local file then it will begin with one of the roots
	* returned by this method. Thus, for example, {@code File} objects
	* denoting the root directories of the mapped network drives of a Windows
	* platform will be returned by this method, while {@code File} objects
	* containing UNC pathnames will not be returned by this method.
	*
	* <p> Unlike most methods in this class, this method does not throw
	* security exceptions. If a security manager exists and its {@link
	* SecurityManager#checkRead(String)} method denies read access to a
	* particular root directory, then that directory will not appear in the
	* result.
	*
	* @return An array of {@code File} objects denoting the available
	* filesystem roots, or {@code null} if the set of roots could not
	* be determined. The array will be empty if there are no
	* filesystem roots.
	*
	* @since 1.2
	* @see java.nio.file.FileStore
	*/
	public static File[] listRoots() {
	return fs.listRoots();
	}


	/* -- Disk usage -- */

	/**
	* Returns the size of the partition <a href="#partName">named</a> by this
	* abstract pathname. If the total number of bytes in the partition is
	* greater than {@link Long#MAX_VALUE}, then {@code Long.MAX_VALUE} will be
	* returned.
	*
	* @return The size, in bytes, of the partition or {@code 0L} if this
	* abstract pathname does not name a partition or if the size
	* cannot be obtained
	*
	* @throws SecurityException
	* If a security manager has been installed and it denies
	* {@link RuntimePermission}{@code ("getFileSystemAttributes")}
	* or its {@link SecurityManager#checkRead(String)} method denies
	* read access to the file named by this abstract pathname
	*
	* @since 1.6
	* @see FileStore#getTotalSpace
	*/
	public long getTotalSpace() {
	@SuppressWarnings("removal")
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	sm.checkPermission(new RuntimePermission("getFileSystemAttributes"));
	sm.checkRead(path);
	}
	if (isInvalid()) {
	return 0L;
	}
	long space = fs.getSpace(this, FileSystem.SPACE_TOTAL);
	return space >= 0L ? space : Long.MAX_VALUE;
	}

	/**
	* Returns the number of unallocated bytes in the partition <a
	* href="#partName">named</a> by this abstract path name. If the
	* number of unallocated bytes in the partition is greater than
	* {@link Long#MAX_VALUE}, then {@code Long.MAX_VALUE} will be returned.
	*
	* <p> The returned number of unallocated bytes is a hint, but not
	* a guarantee, that it is possible to use most or any of these
	* bytes. The number of unallocated bytes is most likely to be
	* accurate immediately after this call. It is likely to be made
	* inaccurate by any external I/O operations including those made
	* on the system outside of this virtual machine. This method
	* makes no guarantee that write operations to this file system
	* will succeed.
	*
	* @return The number of unallocated bytes on the partition or {@code 0L}
	* if the abstract pathname does not name a partition or if this
	* number cannot be obtained. This value will be less than or
	* equal to the total file system size returned by
	* {@link #getTotalSpace}.
	*
	* @throws SecurityException
	* If a security manager has been installed and it denies
	* {@link RuntimePermission}{@code ("getFileSystemAttributes")}
	* or its {@link SecurityManager#checkRead(String)} method denies
	* read access to the file named by this abstract pathname
	*
	* @since 1.6
	* @see FileStore#getUnallocatedSpace
	*/
	public long getFreeSpace() {
	@SuppressWarnings("removal")
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	sm.checkPermission(new RuntimePermission("getFileSystemAttributes"));
	sm.checkRead(path);
	}
	if (isInvalid()) {
	return 0L;
	}
	long space = fs.getSpace(this, FileSystem.SPACE_FREE);
	return space >= 0L ? space : Long.MAX_VALUE;
	}

	/**
	* Returns the number of bytes available to this virtual machine on the
	* partition <a href="#partName">named</a> by this abstract pathname. If
	* the number of available bytes in the partition is greater than
	* {@link Long#MAX_VALUE}, then {@code Long.MAX_VALUE} will be returned.
	* When possible, this method checks for write permissions and other
	* operating system restrictions and will therefore usually provide a more
	* accurate estimate of how much new data can actually be written than
	* {@link #getFreeSpace}.
	*
	* <p> The returned number of available bytes is a hint, but not a
	* guarantee, that it is possible to use most or any of these bytes. The
	* number of available bytes is most likely to be accurate immediately
	* after this call. It is likely to be made inaccurate by any external
	* I/O operations including those made on the system outside of this
	* virtual machine. This method makes no guarantee that write operations
	* to this file system will succeed.
	*
	* @return The number of available bytes on the partition or {@code 0L}
	* if the abstract pathname does not name a partition or if this
	* number cannot be obtained. On systems where this information
	* is not available, this method will be equivalent to a call to
	* {@link #getFreeSpace}.
	*
	* @throws SecurityException
	* If a security manager has been installed and it denies
	* {@link RuntimePermission}{@code ("getFileSystemAttributes")}
	* or its {@link SecurityManager#checkRead(String)} method denies
	* read access to the file named by this abstract pathname
	*
	* @since 1.6
	* @see FileStore#getUsableSpace
	*/
	public long getUsableSpace() {
	@SuppressWarnings("removal")
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	sm.checkPermission(new RuntimePermission("getFileSystemAttributes"));
	sm.checkRead(path);
	}
	if (isInvalid()) {
	return 0L;
	}
	long space = fs.getSpace(this, FileSystem.SPACE_USABLE);
	return space >= 0L ? space : Long.MAX_VALUE;
	}

	/* -- Temporary files -- */

	private static class TempDirectory {
	private TempDirectory() { }

	// temporary directory location
	private static final File tmpdir = new File(
	GetPropertyAction.privilegedGetProperty("java.io.tmpdir"));
	static File location() {
	return tmpdir;
	}

	// file name generation
	private static final SecureRandom random = new SecureRandom();
	private static int shortenSubName(int subNameLength, int excess,
	int nameMin) {
	int newLength = Math.max(nameMin, subNameLength - excess);
	if (newLength < subNameLength) {
	return newLength;
	}
	return subNameLength;
	}
	@SuppressWarnings("removal")
	static File generateFile(String prefix, String suffix, File dir)
	throws IOException
	{
	long n = random.nextLong();
	String nus = Long.toUnsignedString(n);

	// Use only the file name from the supplied prefix
	prefix = (new File(prefix)).getName();

	int prefixLength = prefix.length();
	int nusLength = nus.length();
	int suffixLength = suffix.length();;

	String name;
	int nameMax = fs.getNameMax(dir.getPath());
	int excess = prefixLength + nusLength + suffixLength - nameMax;
	if (excess <= 0) {
	name = prefix + nus + suffix;
	} else {
	// Name exceeds the maximum path component length: shorten it

	// Attempt to shorten the prefix length to no less then 3
	prefixLength = shortenSubName(prefixLength, excess, 3);
	excess = prefixLength + nusLength + suffixLength - nameMax;

	if (excess > 0) {
	// Attempt to shorten the suffix length to no less than
	// 0 or 4 depending on whether it begins with a dot ('.')
	suffixLength = shortenSubName(suffixLength, excess,
	suffix.indexOf(".") == 0 ? 4 : 0);
	suffixLength = shortenSubName(suffixLength, excess, 3);
	excess = prefixLength + nusLength + suffixLength - nameMax;
	}

	if (excess > 0 && excess <= nusLength - 5) {
	// Attempt to shorten the random character string length
	// to no less than 5
	nusLength = shortenSubName(nusLength, excess, 5);
	}

	StringBuilder sb =
	new StringBuilder(prefixLength + nusLength + suffixLength);
	sb.append(prefixLength < prefix.length() ?
	prefix.substring(0, prefixLength) : prefix);
	sb.append(nusLength < nus.length() ?
	nus.substring(0, nusLength) : nus);
	sb.append(suffixLength < suffix.length() ?
	suffix.substring(0, suffixLength) : suffix);
	name = sb.toString();
	}

	// Normalize the path component
	name = fs.normalize(name);

	File f = new File(dir, name);
	if (!name.equals(f.getName()) \|\| f.isInvalid()) {
	if (System.getSecurityManager() != null)
	throw new IOException("Unable to create temporary file");
	else
	throw new IOException("Unable to create temporary file, "
	+ name);
	}
	return f;
	}
	}

	/**
	* <p> Creates a new empty file in the specified directory, using the
	* given prefix and suffix strings to generate its name. If this method
	* returns successfully then it is guaranteed that:
	*
	* <ol>
	* <li> The file denoted by the returned abstract pathname did not exist
	* before this method was invoked, and
	* <li> Neither this method nor any of its variants will return the same
	* abstract pathname again in the current invocation of the virtual
	* machine.
	* </ol>
	*
	* This method provides only part of a temporary-file facility. To arrange
	* for a file created by this method to be deleted automatically, use the
	* {@link #deleteOnExit} method.
	*
	* <p> The {@code prefix} argument must be at least three characters
	* long. It is recommended that the prefix be a short, meaningful string
	* such as {@code "hjb"} or {@code "mail"}. The
	* {@code suffix} argument may be {@code null}, in which case the
	* suffix {@code ".tmp"} will be used.
	*
	* <p> To create the new file, the prefix and the suffix may first be
	* adjusted to fit the limitations of the underlying platform. If the
	* prefix is too long then it will be truncated, but its first three
	* characters will always be preserved. If the suffix is too long then it
	* too will be truncated, but if it begins with a period character
	* ({@code '.'}) then the period and the first three characters
	* following it will always be preserved. Once these adjustments have been
	* made the name of the new file will be generated by concatenating the
	* prefix, five or more internally-generated characters, and the suffix.
	*
	* <p> If the {@code directory} argument is {@code null} then the
	* system-dependent default temporary-file directory will be used. The
	* default temporary-file directory is specified by the system property
	* {@code java.io.tmpdir}. On UNIX systems the default value of this
	* property is typically {@code "/tmp"} or {@code "/var/tmp"}; on
	* Microsoft Windows systems it is typically {@code "C:\\WINNT\\TEMP"}. A different
	* value may be given to this system property when the Java virtual machine
	* is invoked, but programmatic changes to this property are not guaranteed
	* to have any effect upon the temporary directory used by this method.
	*
	* @param prefix The prefix string to be used in generating the file's
	* name; must be at least three characters long
	*
	* @param suffix The suffix string to be used in generating the file's
	* name; may be {@code null}, in which case the
	* suffix {@code ".tmp"} will be used
	*
	* @param directory The directory in which the file is to be created, or
	* {@code null} if the default temporary-file
	* directory is to be used
	*
	* @return An abstract pathname denoting a newly-created empty file
	*
	* @throws IllegalArgumentException
	* If the {@code prefix} argument contains fewer than three
	* characters
	*
	* @throws IOException If a file could not be created
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method does not allow a file to be created
	*
	* @since 1.2
	*/
	public static File createTempFile(String prefix, String suffix,
	File directory)
	throws IOException
	{
	if (prefix.length() < 3) {
	throw new IllegalArgumentException("Prefix string \"" + prefix +
	"\" too short: length must be at least 3");
	}
	if (suffix == null)
	suffix = ".tmp";

	File tmpdir = (directory != null) ? directory
	: TempDirectory.location();
	@SuppressWarnings("removal")
	SecurityManager sm = System.getSecurityManager();
	File f;
	do {
	f = TempDirectory.generateFile(prefix, suffix, tmpdir);

	if (sm != null) {
	try {
	sm.checkWrite(f.getPath());
	} catch (SecurityException se) {
	// don't reveal temporary directory location
	if (directory == null)
	throw new SecurityException("Unable to create temporary file");
	throw se;
	}
	}
	} while (fs.hasBooleanAttributes(f, FileSystem.BA_EXISTS));

	if (!fs.createFileExclusively(f.getPath()))
	throw new IOException("Unable to create temporary file");

	return f;
	}

	/**
	* Creates an empty file in the default temporary-file directory, using
	* the given prefix and suffix to generate its name. Invoking this method
	* is equivalent to invoking {@link #createTempFile(java.lang.String,
	* java.lang.String, java.io.File)
	* createTempFile(prefix, suffix, null)}.
	*
	* <p> The {@link
	* java.nio.file.Files#createTempFile(String,String,java.nio.file.attribute.FileAttribute[])
	* Files.createTempFile} method provides an alternative method to create an
	* empty file in the temporary-file directory. Files created by that method
	* may have more restrictive access permissions to files created by this
	* method and so may be more suited to security-sensitive applications.
	*
	* @param prefix The prefix string to be used in generating the file's
	* name; must be at least three characters long
	*
	* @param suffix The suffix string to be used in generating the file's
	* name; may be {@code null}, in which case the
	* suffix {@code ".tmp"} will be used
	*
	* @return An abstract pathname denoting a newly-created empty file
	*
	* @throws IllegalArgumentException
	* If the {@code prefix} argument contains fewer than three
	* characters
	*
	* @throws IOException If a file could not be created
	*
	* @throws SecurityException
	* If a security manager exists and its {@link
	* java.lang.SecurityManager#checkWrite(java.lang.String)}
	* method does not allow a file to be created
	*
	* @since 1.2
	* @see java.nio.file.Files#createTempDirectory(String,FileAttribute[])
	*/
	public static File createTempFile(String prefix, String suffix)
	throws IOException
	{
	return createTempFile(prefix, suffix, null);
	}

	/* -- Basic infrastructure -- */

	/**
	* Compares two abstract pathnames lexicographically. The ordering
	* defined by this method depends upon the underlying system. On UNIX
	* systems, alphabetic case is significant in comparing pathnames; on
	* Microsoft Windows systems it is not.
	*
	* @param pathname The abstract pathname to be compared to this abstract
	* pathname
	*
	* @return Zero if the argument is equal to this abstract pathname, a
	* value less than zero if this abstract pathname is
	* lexicographically less than the argument, or a value greater
	* than zero if this abstract pathname is lexicographically
	* greater than the argument
	*
	* @since 1.2
	*/
	public int compareTo(File pathname) {
	return fs.compare(this, pathname);
	}

	/**
	* Tests this abstract pathname for equality with the given object.
	* Returns {@code true} if and only if the argument is not
	* {@code null} and is an abstract pathname that is the same as this
	* abstract pathname. Whether or not two abstract
	* pathnames are equal depends upon the underlying operating system.
	* On UNIX systems, alphabetic case is significant in comparing pathnames;
	* on Microsoft Windows systems it is not.
	*
	* @apiNote This method only tests whether the abstract pathnames are equal;
	* it does not access the file system and the file is not required
	* to exist.
	*
	* @param obj The object to be compared with this abstract pathname
	*
	* @return {@code true} if and only if the objects are the same;
	* {@code false} otherwise
	*
	* @see #compareTo(File)
	* @see java.nio.file.Files#isSameFile(Path,Path)
	*/
	public boolean equals(Object obj) {
	if (obj instanceof File file) {
	return compareTo(file) == 0;
	}
	return false;
	}

	/**
	* Computes a hash code for this abstract pathname. Because equality of
	* abstract pathnames is inherently system-dependent, so is the computation
	* of their hash codes. On UNIX systems, the hash code of an abstract
	* pathname is equal to the exclusive <em>or</em> of the hash code
	* of its pathname string and the decimal value
	* {@code 1234321}. On Microsoft Windows systems, the hash
	* code is equal to the exclusive <em>or</em> of the hash code of
	* its pathname string converted to lower case and the decimal
	* value {@code 1234321}. Locale is not taken into account on
	* lowercasing the pathname string.
	*
	* @return A hash code for this abstract pathname
	*/
	public int hashCode() {
	return fs.hashCode(this);
	}

	/**
	* Returns the pathname string of this abstract pathname. This is just the
	* string returned by the {@link #getPath} method.
	*
	* @return The string form of this abstract pathname
	*/
	public String toString() {
	return getPath();
	}

	/**
	* WriteObject is called to save this filename.
	* The separator character is saved also so it can be replaced
	* in case the path is reconstituted on a different host type.
	*
	* @serialData Default fields followed by separator character.
	*
	* @param s the {@code ObjectOutputStream} to which data is written
	* @throws IOException if an I/O error occurs
	*/
	@java.io.Serial
	private synchronized void writeObject(java.io.ObjectOutputStream s)
	throws IOException
	{
	s.defaultWriteObject();
	s.writeChar(separatorChar); // Add the separator character
	}

	/**
	* readObject is called to restore this filename.
	* The original separator character is read. If it is different
	* than the separator character on this system, then the old separator
	* is replaced by the local separator.
	*
	* @param s the {@code ObjectInputStream} from which data is read
	* @throws IOException if an I/O error occurs
	* @throws ClassNotFoundException if a serialized class cannot be loaded
	*/
	@java.io.Serial
	private synchronized void readObject(java.io.ObjectInputStream s)
	throws IOException, ClassNotFoundException
	{
	ObjectInputStream.GetField fields = s.readFields();
	String pathField = (String)fields.get("path", null);
	char sep = s.readChar(); // read the previous separator char
	if (sep != separatorChar)
	pathField = pathField.replace(sep, separatorChar);
	String path = fs.normalize(pathField);
	UNSAFE.putReference(this, PATH_OFFSET, path);
	UNSAFE.putIntVolatile(this, PREFIX_LENGTH_OFFSET, fs.prefixLength(path));
	}

	private static final jdk.internal.misc.Unsafe UNSAFE
	= jdk.internal.misc.Unsafe.getUnsafe();
	private static final long PATH_OFFSET
	= UNSAFE.objectFieldOffset(File.class, "path");
	private static final long PREFIX_LENGTH_OFFSET
	= UNSAFE.objectFieldOffset(File.class, "prefixLength");

	/** use serialVersionUID from JDK 1.0.2 for interoperability */
	@java.io.Serial
	private static final long serialVersionUID = 301077366599181567L;

	// -- Integration with java.nio.file --

	private transient volatile Path filePath;

	/**
	* Returns a {@link Path java.nio.file.Path} object constructed from
	* this abstract path. The resulting {@code Path} is associated with the
	* {@link java.nio.file.FileSystems#getDefault default-filesystem}.
	*
	* <p> The first invocation of this method works as if invoking it were
	* equivalent to evaluating the expression:
	* <blockquote><pre>
	* {@link java.nio.file.FileSystems#getDefault FileSystems.getDefault}().{@link
	* java.nio.file.FileSystem#getPath getPath}(this.{@link #getPath getPath}());
	* </pre></blockquote>
	* Subsequent invocations of this method return the same {@code Path}.
	*
	* <p> If this abstract pathname is the empty abstract pathname then this
	* method returns a {@code Path} that may be used to access the current
	* user directory.
	*
	* @return a {@code Path} constructed from this abstract path
	*
	* @throws java.nio.file.InvalidPathException
	* if a {@code Path} object cannot be constructed from the abstract
	* path (see {@link java.nio.file.FileSystem#getPath FileSystem.getPath})
	*
	* @since 1.7
	* @see Path#toFile
	*/
	public Path toPath() {
	Path result = filePath;
	if (result == null) {
	synchronized (this) {
	result = filePath;
	if (result == null) {
	result = FileSystems.getDefault().getPath(path);
	filePath = result;
	}
	}
	}
	return result;
	}
	}

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