Summary: Constants | Ctors | Methods | Inherited Methods | [Expand All]

public class

File

extends Object
implements Serializable Comparable<T>

java.lang.Object
↳	java.io.File

Class Overview

File is a class which represents a file name or directory. The file may be absolute relative to the root directory of the file system or relative to the current directory in which the program is running.

This class provides methods for querying/changing information about the file and also directory listing capabilities if the File represents a directory.

When manipulating file paths, the static fields of this class may be used to determine the platform specific separators.

Summary

Constants
String	pathSeparator	System dependent path separator String.
char	pathSeparatorChar	System dependent path separator character.
String	separator	System dependent file separator String.
char	separatorChar	System dependent file separator character.

Public Constructors
	File(File dir, String name) Constructs a new File using the specified directory and name.
	File(String path) Constructs a new File using the specified path.
	File(String dirPath, String name) Constructs a new File using the specified directory and name placing a path separator between the two.
	File(URI uri) Constructs a new File using the path of the specified URI `uri` needs to be an absolute and hierarchical `URI` with file scheme, and non-empty path component, but with undefined authority, query or fragment components.

Public Methods
boolean	canRead() Returns a boolean indicating whether or not the current context is allowed to read this File.
boolean	canWrite() Returns a boolean indicating whether or not the current context is allowed to write to this File.
int	compareTo(File another) Returns the relative sort ordering of paths for the receiver and given argument.
boolean	createNewFile() Creates the file specified by this File.
static File	createTempFile(String prefix, String suffix, File directory) Creates an empty temporary file in the given directory using the given prefix and suffix as part of the file name.
static File	createTempFile(String prefix, String suffix) Creates an empty temporary file using the given prefix and suffix as part of the file name.
boolean	delete() Deletes the file specified by this File.
void	deleteOnExit() When the virtual machine terminates, any abstract files which have been sent `deleteOnExit()` will be deleted.
boolean	equals(Object obj) Compares the argument `obj` to the receiver, and returns `true` if they represent the same object using a path specific comparison.
boolean	exists() Returns a boolean indicating whether or not this File can be found on the underlying file system.
File	getAbsoluteFile() Returns a new File constructed using the absolute file path of this File.
String	getAbsolutePath() Returns the absolute file path of this File.
File	getCanonicalFile() Returns a new File created using the canonical file path of this File.
String	getCanonicalPath() Returns the absolute file path of this File with all references resolved.
String	getName() Returns the filename (not directory) of this File.
String	getParent() Returns the pathname of the parent of this File.
File	getParentFile() Returns a new File made from the pathname of the parent of this File.
String	getPath() Returns the file path of this File.
int	hashCode() Returns an integer hash code for the receiver.
boolean	isAbsolute() Returns if this File is an absolute pathname.
boolean	isDirectory() Returns if this File represents a directory on the underlying file system.
boolean	isFile() Returns if this File represents a file on the underlying file system.
boolean	isHidden() Returns whether or not this file is a hidden file as defined by the operating system.
long	lastModified() Returns the time this File was last modified.
long	length() Returns the length of this File in bytes.
String[]	list() Returns an array of Strings representing the file names in the directory represented by this File.
String[]	list(FilenameFilter filter) Returns an array of Strings representing the file names in the directory represented by this File that match a specific filter.
File[]	listFiles(FileFilter filter) Returns an array of Files representing the file names in the directory represented by this File that match a specific filter.
File[]	listFiles(FilenameFilter filter) Returns an array of Files representing the file names in the directory represented by this File that match a specific filter.
File[]	listFiles() Returns an array of Files representing the file names in the directory represented by this File.
static File[]	listRoots() Lists the filesystem roots.
boolean	mkdir() Creates the directory named by the trailing filename of this File.
boolean	mkdirs() Create all the directories needed for this File.
boolean	renameTo(File dest) Renames this File to the name represented by the File `dest`.
boolean	setLastModified(long time) Sets the time this File was last modified.
boolean	setReadOnly() Marks this file or directory to be read-only as defined by the operating system.
String	toString() Returns a string containing a concise, human-readable description of the receiver.
URI	toURI() Returns a `file` URI for this File.
URL	toURL() Returns a `file` URL for this File.

[Expand]

Inherited Methods

From class java.lang.Object

Object	clone() Returns a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o) Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison.
void	finalize() Called by the virtual machine when there are no longer any (non-weak) references to the receiver.
final Class<? extends Object>	getClass() Returns the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode() Returns an integer hash code for the receiver.
final void	notify() Causes one thread which is `wait` ing on the receiver to be made ready to run.
final void	notifyAll() Causes all threads which are `wait` ing on the receiver to be made ready to run.
String	toString() Returns a string containing a concise, human-readable description of the receiver.
final void	wait(long time, int frac) Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by `notify` or `notifyAll`) or the expiration of the timeout.
final void	wait(long time) Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by `notify` or `notifyAll`) or the expiration of the timeout.
final void	wait() Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by `notify` or `notifyAll`).

From interface java.lang.Comparable

Constants

public static final String pathSeparator

System dependent path separator String. The initial value of this field is the System property "path.separator".

public static final char pathSeparatorChar

System dependent path separator character.

public static final String separator

System dependent file separator String. The initial value of this field is the System property "file.separator".

public static final char separatorChar

System dependent file separator character.

Public Constructors

public File (File dir, String name)

Constructs a new File using the specified directory and name.

Parameters

dir	the directory for the file name
name	the file name to be contained in the dir

public File (String path)

Constructs a new File using the specified path.

Parameters

path	the path to be used for the file

public File (String dirPath, String name)

Constructs a new File using the specified directory and name placing a path separator between the two.

Parameters

dirPath	the directory for the file name
name	the file name to be contained in the dir

public File (URI uri)

Constructs a new File using the path of the specified URI uri needs to be an absolute and hierarchical URI with file scheme, and non-empty path component, but with undefined authority, query or fragment components.

Parameters

uri	the URI instance which will be used to construct this file

Throws

IllegalArgumentException	if `uri` does not comply with the conditions above.

Public Methods

public boolean canRead ()

Returns a boolean indicating whether or not the current context is allowed to read this File.

Returns

true if this File can be read, false otherwise.

public boolean canWrite ()

Returns a boolean indicating whether or not the current context is allowed to write to this File.

Returns

true if this File can be written, false otherwise.

public int compareTo (File another)

Returns the relative sort ordering of paths for the receiver and given argument. The ordering is platform dependent.

Parameters

another	a File to compare the receiver to

Returns

an int determined by comparing the two paths. The meaning is described in the Comparable interface.

public boolean createNewFile ()

Creates the file specified by this File. If the file already exists this method returns false. Otherwise, if the file is created successfully, the result is true. An IOException will be thrown if the directory to contain this file does not exist.

Returns

true if this File was created, false otherwise.

Throws

IOException	if an I/O error occurs or the directory does not exist.

public static File createTempFile (String prefix, String suffix, File directory)

Creates an empty temporary file in the given directory using the given prefix and suffix as part of the file name.

Parameters

prefix	the prefix to the temp file name
suffix	the suffix to the temp file name
directory	the location to which the temp file is to be written, or null for the default temp location

Returns

the temporary file

Throws

IOException	If an error occurs when writing the file

public static File createTempFile (String prefix, String suffix)

Creates an empty temporary file using the given prefix and suffix as part of the file name. If suffix is null, .tmp is used.

Parameters

prefix	the prefix to the temp file name
suffix	the suffix to the temp file name

Returns

the temporary file

Throws

IOException	If an error occurs when writing the file

public boolean delete ()

Deletes the file specified by this File. Directories must be empty before they will be deleted.

Returns

true if this File was deleted, false otherwise.

Throws

SecurityException	in case a `SecurityManager` is installed, and it denies the request.

public void deleteOnExit ()

When the virtual machine terminates, any abstract files which have been sent deleteOnExit() will be deleted. This will only happen when the virtual machine terminates normally as described by the Java Language Specification section 12.9.

Throws

SecurityException	in case a `SecurityManager` is installed, and it denies the request.

public boolean equals (Object obj)

Compares the argument obj to the receiver, and returns true if they represent the same object using a path specific comparison.

Parameters

obj	the Object to compare with this Object

Returns

true if the object is the same as this object, false otherwise.

public boolean exists ()

Returns a boolean indicating whether or not this File can be found on the underlying file system.

Returns

true if this File exists, false otherwise.

public File getAbsoluteFile ()

Returns a new File constructed using the absolute file path of this File.

Returns

a new File from this absolute file path

public String getAbsolutePath ()

Returns the absolute file path of this File.

Returns

the absolute file path

public File getCanonicalFile ()

Returns a new File created using the canonical file path of this File. Equivalent to new File(this.getCanonicalPath()).

Returns

the canonical file path

Throws

IOException	If an IO error occurs

public String getCanonicalPath ()

Returns the absolute file path of this File with all references resolved. An absolute file path is one which begins at the root of the file system. The canonical path is one in which all references have been resolved. For the cases of '..' and '.' where the file system supports parent and working directory respectively, these should be removed and replaced with a direct directory reference. If the File does not exist, getCanonicalPath() may not resolve any references and simply return an absolute path name or throw an IOException.

Returns

the canonical file path

Throws

IOException	if an IO error occurs

public String getName ()

Returns the filename (not directory) of this File.

Returns

the filename or empty string

public String getParent ()

Returns the pathname of the parent of this File. This is the path up to but not including the last name. null is returned when there is no parent.

Returns

the parent name or null

public File getParentFile ()

Returns a new File made from the pathname of the parent of this File. This is the path up to but not including the last name. null is returned when there is no parent.

Returns

a new File representing parent or null

public String getPath ()

Returns the file path of this File.

Returns

the file path

public int hashCode ()

Returns an integer hash code for the receiver. Any two objects which answer true when passed to equals must answer the same value for this method.

Returns

the receiver's hash

public boolean isAbsolute ()

Returns if this File is an absolute pathname. Whether a pathname is absolute is platform specific. On UNIX it is if the path starts with the character '/', on Windows it is absolute if either it starts with '\', '/', '\\' (to represent a file server), or a letter followed by a colon.

Returns

true if this File is absolute, false otherwise.

public boolean isDirectory ()

Returns if this File represents a directory on the underlying file system.

Returns

true if this File is a directory, false otherwise.

public boolean isFile ()

Returns if this File represents a file on the underlying file system.

Returns

true if this File is a file, false otherwise.

public boolean isHidden ()

Returns whether or not this file is a hidden file as defined by the operating system.

Returns

true if the file is hidden, false otherwise.

public long lastModified ()

Returns the time this File was last modified.

Returns

the time this File was last modified.

public long length ()

Returns the length of this File in bytes.

Returns

the number of bytes in the file.

public String[] list ()

Returns an array of Strings representing the file names in the directory represented by this File. If this File is not a directory the result is null.

The entries . and .. representing current directory and parent directory are not returned as part of the list.

Returns

an array of Strings or null.

public String[] list (FilenameFilter filter)

Returns an array of Strings representing the file names in the directory represented by this File that match a specific filter. If this File is not a directory the result is null. If the filter is null then all filenames match.

The entries . and .. representing current directory and parent directory are not returned as part of the list.

Parameters

filter	the filter to match names to or `null`.

Returns

an array of Strings or null.

public File[] listFiles (FileFilter filter)

Returns an array of Files representing the file names in the directory represented by this File that match a specific filter. If this File is not a directory the result is null. If the filter is null then all filenames match.

The entries . and .. representing current directory and parent directory are not returned as part of the list.

Parameters

filter	the filter to match names to or `null`.

Returns

an array of Files or null.

public File[] listFiles (FilenameFilter filter)

Returns an array of Files representing the file names in the directory represented by this File that match a specific filter. If this File is not a directory the result is null. If the filter is null then all filenames match.

The entries . and .. representing current directory and parent directory are not returned as part of the list.

Parameters

filter	the filter to match names to or `null`.

Returns

an array of Files or null.

public File[] listFiles ()

Returns an array of Files representing the file names in the directory represented by this File. If this File is not a directory the result is null. The Files returned will be absolute if this File is absolute, relative otherwise.

Returns

an array of Files or null.

public static File[] listRoots ()

Lists the filesystem roots. The Java platform may support zero or more filesystems, each with its own platform-dependent root. Further, the canonical pathname of any file on the system will always begin with one of the returned filesystem roots.

Returns

the array of filesystem roots

public boolean mkdir ()

Creates the directory named by the trailing filename of this File. Not all directories required to create this File are created.

Returns

true if the directory was created, false otherwise.

public boolean mkdirs ()

Create all the directories needed for this File. If the terminal directory already exists, answer false. If the directories were created successfully, answer true.

Returns

true if the necessary directories were created, false otherwise.

public boolean renameTo (File dest)

Renames this File to the name represented by the File dest. This works for both normal files and directories.

Parameters

dest	the File containing the new name.

Returns

true if the File was renamed, false otherwise.

public boolean setLastModified (long time)

Sets the time this File was last modified.

Parameters

time	The time to set the file as last modified.

Returns

the time this File was last modified.

public boolean setReadOnly ()

Marks this file or directory to be read-only as defined by the operating system.

Returns

true if the operation was a success, false otherwise

public String toString ()

Returns a string containing a concise, human-readable description of the receiver.

Returns

a printable representation for the receiver.

public URI toURI ()

Returns a file URI for this File. The URI is System dependent and may not be transferable between different operating/file systems.

Returns

a file URI for this File.

public URL toURL ()

Returns a file URL for this File. The URL is System dependent and may not be transferable between different operating/file systems.

Returns

a file URL for this File.

Throws

MalformedURLException	if the path cannot be transformed into an URL

Jan	FEB	Mar
	21
2008	2009	2010

Interfaces

Classes

Exceptions

File

Class Overview

See Also

Summary

Constants

public static final String pathSeparator

public static final char pathSeparatorChar

public static final String separator

public static final char separatorChar

Public Constructors

public File (File dir, String name)

Parameters

public File (String path)

Parameters

public File (String dirPath, String name)

Parameters

public File (URI uri)

Parameters

Throws

See Also

Public Methods

public boolean canRead ()

Returns

See Also

public boolean canWrite ()

Returns

See Also

public int compareTo (File another)

Parameters

Returns

See Also

public boolean createNewFile ()

Returns

Throws

See Also

public static File createTempFile (String prefix, String suffix, File directory)

Parameters

Returns

Throws

public static File createTempFile (String prefix, String suffix)

Parameters

Returns

Throws

public boolean delete ()

Returns

Throws

See Also

public void deleteOnExit ()

Throws

public boolean equals (Object obj)

Parameters

Returns

public boolean exists ()

Returns

See Also

public File getAbsoluteFile ()

Returns

See Also

public String getAbsolutePath ()

Returns

See Also

public File getCanonicalFile ()

Returns

Throws

See Also

public String getCanonicalPath ()

Returns

Throws

See Also

public String getName ()

Returns

public String getParent ()

Returns

public File getParentFile ()

Returns

public String getPath ()

Returns