java.io
public class File extends Object implements Serializable, Comparable
Field Summary | |
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static String | pathSeparator
This is the string that is used to separate the host name from the
path name in paths than include the host name. |
static char | pathSeparatorChar
This is the first character of the string used to separate the host name
from the path name in paths that include a host. |
static String | separator
This is the path separator string for the current host. |
static char | separatorChar
This is the first character of the file separator string. |
Constructor Summary | |
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File(String name)
This method initializes a new File object to represent
a file with the specified path.
| |
File(String dirPath, String name)
This method initializes a new File object to represent
a file in the specified named directory. | |
File(File directory, String name)
This method initializes a new File object to represent
a file in the specified directory. | |
File(URI uri)
This method initializes a new File object to represent
a file corresponding to the specified file: protocol URI.
|
Method Summary | |
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boolean | canRead()
This method tests whether or not the current thread is allowed to
to read the file pointed to by this object. |
boolean | canWrite()
This method test whether or not the current thread is allowed to
write to this object. |
int | compareTo(File other)
This method compares the specified File to this one
to test for equality. |
int | compareTo(Object obj)
This method compares the specified Object to this one
to test for equality. |
boolean | createNewFile()
This method creates a new file of zero length with the same name as
the path of this File object if an only if that file
does not already exist.
|
static File | createTempFile(String prefix, String suffix, File directory)
This method creates a temporary file in the specified directory. |
static File | createTempFile(String prefix, String suffix)
This method creates a temporary file in the system temporary directory.
|
boolean | delete()
This method deletes the file represented by this object. |
void | deleteOnExit()
Calling this method requests that the file represented by this object
be deleted when the virtual machine exits. |
boolean | equals(Object obj)
This method tests two File objects for equality by
comparing the path of the specified File against the path
of this object. |
boolean | exists()
This method tests whether or not the file represented by the object
actually exists on the filesystem.
|
File | getAbsoluteFile()
This method returns a File object representing the
absolute path of this object.
|
String | getAbsolutePath()
This method returns the path of this file as an absolute path name.
|
File | getCanonicalFile()
This method returns a File object representing the
canonical path of this object.
|
String | getCanonicalPath()
This method returns a canonical representation of the pathname of
this file. |
String | getName()
This method returns the name of the file. |
String | getParent()
This method returns a String the represents this file's
parent. |
File | getParentFile()
This method returns a File object representing the parent
file of this one.
|
String | getPath()
Returns the path name that represents this file. |
int | hashCode()
This method returns a hash code representing this file. |
boolean | isAbsolute()
This method returns true if this object represents an absolute file
path and false if it does not. |
boolean | isDirectory()
This method tests whether or not the file represented by this object
is a directory. |
boolean | isFile()
This method tests whether or not the file represented by this object
is a "plain" file. |
boolean | isHidden()
This method tests whether or not this file represents a "hidden" file.
|
long | lastModified()
This method returns the last modification time of this file. |
long | length()
This method returns the length of the file represented by this object,
or 0 if the specified file does not exist.
|
String[] | list(FilenameFilter filter)
This method returns a array of String 's representing the
list of files is then directory represented by this object. |
String[] | list()
This method returns a array of String 's representing the
list of files is then directory represented by this object. |
File[] | listFiles()
This method returns an array of File objects representing
all the files in the directory represented by this object. |
File[] | listFiles(FilenameFilter filter)
This method returns an array of File objects representing
all the files in the directory represented by this object. |
File[] | listFiles(FileFilter filter)
This method returns an array of File objects representing
all the files in the directory represented by this object. |
static File[] | listRoots()
This method returns an array of filesystem roots. |
boolean | mkdir()
This method creates a directory for the path represented by this object.
|
boolean | mkdirs()
This method creates a directory for the path represented by this file.
|
boolean | renameTo(File dest)
This method renames the file represented by this object to the path
of the file represented by the argument File .
|
boolean | setLastModified(long time)
This method sets the modification time on the file to the specified
value. |
boolean | setReadOnly()
This method sets the file represented by this object to be read only.
|
String | toString()
This method returns a String that is the path name of the
file as returned by getPath .
|
URI | toURI() |
URL | toURL()
This method returns a URL with the file:
protocol that represents this file. |
path.separator
system property.path.separator
system property.file.separator
system property.
An example separator string would be "/" on the GNU system.file.separator
system property.File
object to represent
a file with the specified path.
Parameters: name The path name of the file
File
object to represent
a file in the specified named directory. The path name to the file
will be the directory name plus the separator string plus the file
name. If the directory path name ends in the separator string, another
separator string will still be appended.
Parameters: dirPath The path to the directory the file resides in name The name of the file
File
object to represent
a file in the specified directory. If the directory
argument is null
, the file is assumed to be in the
current directory as specified by the user.dir
system
property
Parameters: directory The directory this file resides in name The name of the file
File
object to represent
a file corresponding to the specified file:
protocol URI.
Parameters: uri The uri.
SecurityManager
(if any) allows access to the file via it's checkRead
method 3) the file is readable.
Returns: true
if reading is allowed,
false
otherwise
Throws: SecurityException If the SecurityManager
does not allow access to the file
SecurityManager
(if any) allows write access to the
file and 2) The file exists and 3) The file is writable. To determine
whether or not a non-existent file can be created, check the parent
directory for write access.
Returns: true
if writing is allowed, false
otherwise
Throws: SecurityException If the SecurityManager
does not allow access to the file
File
to this one
to test for equality. It does this by comparing the canonical path names
of the files.
The canonical paths of the files are determined by calling the
getCanonicalPath
method on each object.
This method returns a 0 if the specified Object
is equal
to this one, a negative value if it is less than this one
a positive value if it is greater than this one.
Returns: An integer as described above
Since: 1.2
Object
to this one
to test for equality. It does this by comparing the canonical path names
of the files. This method is identical to compareTo(File)
except that if the Object
passed to it is not a
File
, it throws a ClassCastException
The canonical paths of the files are determined by calling the
getCanonicalPath
method on each object.
This method returns a 0 if the specified Object
is equal
to this one, a negative value if it is less than this one
a positive value if it is greater than this one.
Returns: An integer as described above
Throws: ClassCastException If the passed Object
is
not a File
Since: 1.2
File
object if an only if that file
does not already exist.
A SecurityManager.checkWrite
check is done prior
to performing this action.
Returns: true
if the file was created, false
if
the file alread existed.
Throws: IOException If an I/O error occurs SecurityException If the SecurityManager
will
not allow this operation to be performed.
Since: 1.2
java.io.tmpdir
system property.
The prefix
parameter is a sequence of at least three
characters that are used as the start of the generated filename. The
suffix
parameter is a sequence of characters that is used
to terminate the file name. This parameter may be null
and if it is, the suffix defaults to ".tmp".
If a SecurityManager
exists, then its checkWrite
method is used to verify that this operation is permitted.
Parameters: prefix The character prefix to use in generating the path name. suffix The character suffix to use in generating the path name. directory The directory to create the file in, or
null
for the default temporary directory
Throws: IllegalArgumentException If the patterns is not valid SecurityException If there is no permission to perform this operation IOException If an error occurs
Since: 1.2
java.io.tmpdir
system property.
The prefix
parameter is a sequence of at least three
characters that are used as the start of the generated filename. The
suffix
parameter is a sequence of characters that is used
to terminate the file name. This parameter may be null
and if it is, the suffix defaults to ".tmp".
If a SecurityManager
exists, then its checkWrite
method is used to verify that this operation is permitted.
This method is identical to calling
createTempFile(prefix, suffix, null)
.
Parameters: prefix The character prefix to use in generating the path name. suffix The character suffix to use in generating the path name.
Throws: IllegalArgumentException If the prefix or suffix are not valid. SecurityException If there is no permission to perform this operation IOException If an error occurs
Returns: true
if the file was deleted, false
otherwise
Throws: SecurityException If deleting of the file is not allowed
Throws: SecurityException If deleting of the file is not allowed
Since: 1.2
File
objects for equality by
comparing the path of the specified File
against the path
of this object. The two objects are equal if an only if 1) The
argument is not null 2) The argument is a File
object and
3) The path of the File
argument is equal to the path
of this object.
The paths of the files are determined by calling the
getPath()
method on each object.
Returns: true
if the two objects are equal,
false
otherwise.
Returns: true
if the file exists, false
otherwise.
Throws: SecurityException If reading of the file is not permitted
File
object representing the
absolute path of this object.
Returns: A File
with the absolute path of the object.
Since: 1.2
user.dir
system property.
Returns: The absolute path of this file
File
object representing the
canonical path of this object.
Returns: A File
instance representing the canonical path of
this object.
Throws: IOException If an error occurs.
Since: 1.2
Note that this method, unlike the other methods which return path names, can throw an IOException. This is because native method might be required in order to resolve the canonical path
Throws: IOException If an error occurs
Returns: The file name
String
the represents this file's
parent. null
is returned if the file has no parent. The
parent is determined via a simple operation which removes the
Returns: The parent directory of this file
File
object representing the parent
file of this one.
Returns: a File
for the parent of this object.
null
will be returned if this object does not have a parent.
Since: 1.2
Returns: The pathname of this file
getPath()
)
exclusived or-ed with the value 1234321.
Returns: The hash code for this object
Returns: true
if this object represents an absolute
file name, false
otherwise.
true
,
the file represented by this object must exist and be a directory.
Returns: true
if this file is a directory, false
otherwise
Throws: SecurityException If reading of the file is not permitted
Returns: true
if this is a plain file, false
otherwise
Throws: SecurityException If reading of the file is not permitted
Returns: true
if the file is hidden, false
otherwise.
Since: 1.2
If the file does not exist, then a value of 0 is returned.
Returns: The last modification time of the file
Throws: SecurityException If reading of the file is not permitted
Returns: The length of the file
Throws: SecurityException If reading of the file is not permitted
String
's representing the
list of files is then directory represented by this object. If this
object represents a non-directory file or a non-existent file, then
null
is returned. The list of files will not contain
any names such as "." or ".." which indicate the current or parent
directory. Also, the names are not guaranteed to be sorted.
In this form of the list()
method, a filter is specified
that allows the caller to control which files are returned in the
list. The FilenameFilter
specified is called for each
file returned to determine whether or not that file should be included
in the list.
A SecurityManager
check is made prior to reading the
directory. If read access to the directory is denied, an exception
will be thrown.
Parameters: filter An object which will identify files to exclude from the directory listing.
Returns: An array of files in the directory, or null
if this object does not represent a valid directory.
Throws: SecurityException If read access is not allowed to the
directory by the SecurityManager
String
's representing the
list of files is then directory represented by this object. If this
object represents a non-directory file or a non-existent file, then
null
is returned. The list of files will not contain
any names such as "." or ".." which indicate the current or parent
directory. Also, the names are not guaranteed to be sorted.
A SecurityManager
check is made prior to reading the
directory. If read access to the directory is denied, an exception
will be thrown.
Returns: An array of files in the directory, or null
if
this object does not represent a valid directory.
Throws: SecurityException If read access is not allowed to the
directory by the SecurityManager
File
objects representing
all the files in the directory represented by this object. If this
object does not represent a directory, null
is returned.
Each of the returned File
object is constructed with this
object as its parent.
A SecurityManager
check is made prior to reading the
directory. If read access to the directory is denied, an exception
will be thrown.
Returns: An array of File
objects for this directory.
Throws: SecurityException If the SecurityManager
denies
access to this directory.
Since: 1.2
File
objects representing
all the files in the directory represented by this object. If this
object does not represent a directory, null
is returned.
Each of the returned File
object is constructed with this
object as its parent.
In this form of the listFiles()
method, a filter is specified
that allows the caller to control which files are returned in the
list. The FilenameFilter
specified is called for each
file returned to determine whether or not that file should be included
in the list.
A SecurityManager
check is made prior to reading the
directory. If read access to the directory is denied, an exception
will be thrown.
Returns: An array of File
objects for this directory.
Throws: SecurityException If the SecurityManager
denies
access to this directory.
Since: 1.2
File
objects representing
all the files in the directory represented by this object. If this
object does not represent a directory, null
is returned.
Each of the returned File
object is constructed with this
object as its parent.
In this form of the listFiles()
method, a filter is specified
that allows the caller to control which files are returned in the
list. The FileFilter
specified is called for each
file returned to determine whether or not that file should be included
in the list.
A SecurityManager
check is made prior to reading the
directory. If read access to the directory is denied, an exception
will be thrown.
Returns: An array of File
objects for this directory.
Throws: SecurityException If the SecurityManager
denies
access to this directory.
Since: 1.2
Returns: An array of File
objects for each filesystem root
available.
Since: 1.2
Returns: true
if the directory was created,
false
otherwise
Throws: SecurityException If write access is not allowed to this file
Returns: true
if the directory was created,
false
otherwise
Throws: SecurityException If write access is not allowed to this file
File
.
Parameters: dest The File
object representing the target name
Returns: true
if the rename succeeds, false
otherwise.
Throws: SecurityException If write access is not allowed to the
file by the SecurityMananger
.
Parameters: time The desired modification time.
Returns: true
if the operation succeeded, false
otherwise.
Throws: IllegalArgumentException If the specified time is negative. SecurityException If the SecurityManager
will
not allow this operation.
Since: 1.2
Returns: true
if the operation succeeded, false
otherwise.
Throws: SecurityException If the SecurityManager
does
not allow this operation.
Since: 1.2
String
that is the path name of the
file as returned by getPath
.
Returns: A String
representation of this file
Returns: A URI
for this object.
URL
with the file:
protocol that represents this file. The exact form of this URL is
system dependent.
Returns: A URL
for this object.
Throws: MalformedURLException If the URL cannot be created successfully.