|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Objectjava.io.File
public class File
This class represents a file or directory on a local disk. It provides facilities for dealing with a variety of systems that use various types of path separators ("/" versus "\", for example). It also contains method useful for creating and deleting files and directories.
Field Summary | |
---|---|
static String |
pathSeparator
This is the string that is used to separate the host name from the path name in paths that 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 | |
---|---|
File(File directory,
String name)
This method initializes a new File object to represent
a file in the specified directory. |
|
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(URI uri)
This method initializes a new File object to represent
a file corresponding to the specified file: protocol URI. |
Method Summary | |
---|---|
boolean |
canExecute()
This method tests whether or not the current thread is allowed to to execute the file pointed to by this object. |
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. |
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)
This method creates a temporary file in the system temporary directory. |
static File |
createTempFile(String prefix,
String suffix,
File directory)
This method creates a temporary file in the specified 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()
This method returns a array of String 's representing the
list of files is then directory represented by this object. |
String[] |
list(FilenameFilter filter)
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(FileFilter filter)
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. |
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 |
setExecutable(boolean executable)
This method sets the owner's execute permission for the File represented by this object. |
boolean |
setExecutable(boolean executable,
boolean ownerOnly)
This method sets the execute permissions for the File represented by this object. |
boolean |
setLastModified(long time)
This method sets the modification time on the file to the specified value. |
boolean |
setReadable(boolean readable)
This method sets the owner's read permission for the File represented by this object. |
boolean |
setReadable(boolean readable,
boolean ownerOnly)
This method sets the read permissions for the File represented by this object. |
boolean |
setReadOnly()
This method sets the file represented by this object to be read only. |
boolean |
setWritable(boolean writable)
This method sets the owner's write permission for the File represented by this object. |
boolean |
setWritable(boolean writable,
boolean ownerOnly)
This method sets the write permissions for the File represented by this object. |
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. |
Methods inherited from class java.lang.Object |
---|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Field Detail |
---|
public static final String separator
file.separator
system property.
An example separator string would be "/" on the GNU system.
public static final char separatorChar
file.separator
system property.
public static final String pathSeparator
path.separator
system property.
public static final char pathSeparatorChar
path.separator
system property.
Constructor Detail |
---|
public File(String name)
File
object to represent
a file with the specified path.
name
- The path name of the filepublic File(String dirPath, String name)
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.
dirPath
- The path to the directory the file resides inname
- The name of the filepublic File(File directory, String name)
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
directory
- The directory this file resides inname
- The name of the filepublic File(URI uri)
File
object to represent
a file corresponding to the specified file:
protocol URI.
uri
- The URI
IllegalArgumentException
- if the URI is not hierarchicalMethod Detail |
---|
public boolean canRead()
SecurityManager
(if any) allows access to the file via it's checkRead
method 3) the file is readable.
true
if reading is allowed,
false
otherwise
SecurityException
- If the SecurityManager
does not allow access to the filepublic boolean canWrite()
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.
true
if writing is allowed, false
otherwise
SecurityException
- If the SecurityManager
does not allow access to the filepublic boolean canExecute()
SecurityManager
(if any) allows access to the file via it's checkExec
method 3) the file is executable.
true
if execution is allowed,
false
otherwise
SecurityException
- If the SecurityManager
does not allow access to the filepublic boolean createNewFile() throws IOException
File
object if an only if that file
does not already exist.
A SecurityManager.checkWrite
check is done prior
to performing this action.
true
if the file was created, false
if
the file alread existed.
IOException
- If an I/O error occurs
SecurityException
- If the SecurityManager
will
not allow this operation to be performed.public boolean delete()
true
if the file was deleted, false
otherwise
SecurityException
- If deleting of the file is not allowedpublic boolean equals(Object obj)
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.
equals
in class Object
obj
- the Object to compare to
true
if the two objects are equal,
false
otherwise.Object.hashCode()
public boolean exists()
true
if the file exists, false
otherwise.
SecurityException
- If reading of the file is not permittedpublic String getAbsolutePath()
user.dir
system property.
public File getAbsoluteFile()
File
object representing the
absolute path of this object.
File
with the absolute path of the object.public String getCanonicalPath() throws IOException
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
IOException
- If an error occurspublic File getCanonicalFile() throws IOException
File
object representing the
canonical path of this object.
File
instance representing the canonical path of
this object.
IOException
- If an error occurs.public String getName()
public String getParent()
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 name
after the last file separator character, as determined by the platform.
public File getParentFile()
File
object representing the parent
file of this one.
File
for the parent of this object.
null
will be returned if this object does not have a parent.public String getPath()
public int hashCode()
getPath()
)
exclusived or-ed with the value 1234321.
hashCode
in class Object
Object.equals(Object)
,
System.identityHashCode(Object)
public boolean isAbsolute()
true
if this object represents an absolute
file name, false
otherwise.public boolean isDirectory()
true
,
the file represented by this object must exist and be a directory.
true
if this file is a directory, false
otherwise
SecurityException
- If reading of the file is not permittedpublic boolean isFile()
true
if this is a plain file, false
otherwise
SecurityException
- If reading of the file is not permittedpublic boolean isHidden()
true
if the file is hidden, false
otherwise.public long lastModified()
If the file does not exist, then a value of 0 is returned.
SecurityException
- If reading of the file is not permittedpublic long length()
SecurityException
- If reading of the file is not permittedpublic String[] list(FilenameFilter filter)
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.
filter
- An object which will identify files to exclude from
the directory listing.
null
if this object does not represent a valid directory.
SecurityException
- If read access is not allowed to the
directory by the SecurityManager
public String[] list()
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.
null
if
this object does not represent a valid directory.
SecurityException
- If read access is not allowed to the
directory by the SecurityManager
public File[] listFiles()
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.
File
objects for this directory.
SecurityException
- If the SecurityManager
denies
access to this directory.public File[] listFiles(FilenameFilter filter)
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.
File
objects for this directory.
SecurityException
- If the SecurityManager
denies
access to this directory.public File[] listFiles(FileFilter filter)
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.
File
objects for this directory.
SecurityException
- If the SecurityManager
denies
access to this directory.public String toString()
String
that is the path name of the
file as returned by getPath
.
toString
in class Object
String
representation of this fileObject.getClass()
,
Object.hashCode()
,
Class.getName()
,
Integer.toHexString(int)
public URI toURI()
URI
for this object.public URL toURL() throws MalformedURLException
URL
with the file:
protocol that represents this file. The exact form of this URL is
system dependent.
URL
for this object.
MalformedURLException
- If the URL cannot be created
successfully.public boolean mkdir()
true
if the directory was created,
false
otherwise
SecurityException
- If write access is not allowed to this filepublic boolean mkdirs()
true
if the directory was created,
false
otherwise
SecurityException
- If write access is not allowed to this filepublic static File createTempFile(String prefix, String suffix, File directory) throws IOException
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.
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
IllegalArgumentException
- If the patterns is not valid
SecurityException
- If there is no permission to perform
this operation
IOException
- If an error occurspublic boolean setReadable(boolean readable)
setReadable(readable, true)
.
readable
- true
to set read permission,
false
to unset the read permission.
true
if the file permissions are changed,
false
otherwise.
SecurityException
- If write access of the file is not permitted.setReadable(boolean, boolean)
public boolean setReadable(boolean readable, boolean ownerOnly)
ownerOnly
is set to true
then only the
read permission bit for the owner of the file is changed.
If ownerOnly
is set to false
, the file
permissions are changed so that the file can be read by everyone.
On unix like systems this sets the user
, group
and other
read bits and is equal to call
chmod a+r
on the file.
readable
- true
to set read permission,
false
to unset the read permission.ownerOnly
- true
to set read permission
for owner only, false
for all.
true
if the file permissions are changed,
false
otherwise.
SecurityException
- If write access of the file is not permitted.setReadable(boolean)
public boolean setWritable(boolean writable)
setWritable(readable, true)
.
writable
- true
to set write permission,
false
to unset write permission.
true
if the file permissions are changed,
false
otherwise.
SecurityException
- If write access of the file is not permitted.setWritable(boolean, boolean)
public boolean setWritable(boolean writable, boolean ownerOnly)
ownerOnly
is set to true
then only the
write permission bit for the owner of the file is changed.
If ownerOnly
is set to false
, the file
permissions are changed so that the file can be written by everyone.
On unix like systems this set the user
, group
and other
write bits and is equal to call
chmod a+w
on the file.
writable
- true
to set write permission,
false
to unset write permission.ownerOnly
- true
to set write permission
for owner only, false
for all.
true
if the file permissions are changed,
false
otherwise.
SecurityException
- If write access of the file is not permitted.setWritable(boolean)
public boolean setExecutable(boolean executable)
setExecutable(readable, true)
.
executable
- true
to set execute permission,
false
to unset execute permission.
true
if the file permissions are changed,
false
otherwise.
SecurityException
- If write access of the file is not permitted.setExecutable(boolean, boolean)
public boolean setExecutable(boolean executable, boolean ownerOnly)
ownerOnly
is set to true
then only the
execute permission bit for the owner of the file is changed.
If ownerOnly
is set to false
, the file
permissions are changed so that the file can be executed by everyone.
On unix like systems this set the user
, group
and other
write bits and is equal to call
chmod a+x
on the file.
executable
- true
to set write permission,
false
to unset write permission.ownerOnly
- true
to set write permission
for owner only, false
for all.
true
if the file permissions are changed,
false
otherwise.
SecurityException
- If write access of the file is not permitted.setExecutable(boolean)
public boolean setReadOnly()
true
if the operation succeeded, false
otherwise.
SecurityException
- If the SecurityManager
does
not allow this operation.public static File[] listRoots()
File
objects for each filesystem root
available.public static File createTempFile(String prefix, String suffix) throws IOException
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)
.
prefix
- The character prefix to use in generating the path name.suffix
- The character suffix to use in generating the path name.
IllegalArgumentException
- If the prefix or suffix are not valid.
SecurityException
- If there is no permission to perform
this operation
IOException
- If an error occurspublic int compareTo(File other)
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.
compareTo
in interface Comparable<File>
other
- the object to be compared
public boolean renameTo(File dest)
File
.
dest
- The File
object representing the target name
true
if the rename succeeds, false
otherwise.
SecurityException
- If write access is not allowed to the
file by the SecurityMananger
.public boolean setLastModified(long time)
time
- The desired modification time.
true
if the operation succeeded, false
otherwise.
IllegalArgumentException
- If the specified time is negative.
SecurityException
- If the SecurityManager
will
not allow this operation.public void deleteOnExit()
SecurityException
- If deleting of the file is not allowed
|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |