Once you have a File object in place, there are a
number of questions you can ask about it and things you can do with
it.
public String getName()
The most basic question you can ask a file is, "What is your name?"
You do this with the getName() method which takes no
arguments and returns a String. This String is just the
name of the file. It does not include any piece of the directory or
directories that contain this file. In other words you get back
"file1" instead of "/home/users/elharo/file1."
public String getPath()
getPath() returns a String that contains
the path being used for this File. It will be relative
or absolute depending on how the File object was
created.
public String getAbsolutePath()
getAbsolutePath() returns the complete, non-relative
path to the file.
public String getCanonicalPath() throws
IOException
getCanonicalPath() returns the canonical form of this
File object's pathname. This is system-dependent.
public String getParent()
getParent() returns a String that
contains the name of the single directory which contains this file
in the hierarchy. It does not return a full path all the way back
up to the root. If the file is at the top level of the disk then it
has no parent directory and null is returned.
public boolean exists() throws
SecurityException
The exists() method indicates whether or not a
particular file exists where you expect it to be.
public boolean canWrite() throws
SecurityException
The canWrite() method indicates whether you have write
access to this file. It's not a bad idea to check canWrite() before trying to put data in a file.
public boolean canRead() throws
SecurityException
The canRead() method indicates whether you have read
access to this file. It's not a bad idea to check canRead() before trying to read data out of a file.
public boolean isFile() throws
SecurityException
The isFile() method indicates whether this is file
exists and is a normal file, in other words not a directory.
public boolean isDirectory() throws
SecurityException
The isDirectory() returns true if this
file exists and is a directory.
public boolean isAbsolute()
isAbsolute() returns true if the file
name is an absolute path and false if it's a relative
path.
public long lastModified() throws
SecurityException
lastModified() returns the last modification time.
Since the conversion between this long and a real date is platform
dependent, you should only use this to compare modification dates.
public long length() throws SecurityException
f.length() is the number of bytes in the file.
public boolean mkdir()
f.mkdir() tries to create a directory with the given
name. If the directory is created, the method returns true. Otherwise it returns false.
public boolean mkdirs() throws
SecurityException
mkdirs() creates not just one but every
directory in the path as necessary, permissions permitting.
mkdirs() returns true if all directories in
this path are created, and false if only some or none
of them are created. You may need to manually test the existence of
each directory in the path if the method returns false
because it could have been partially successful.
public boolean renameTo(File destination) throws
SecurityException
f1.renameTo(f2) tries to change the name of f1 to f2.
This may involve a move to a different directory if the filenames
so indicate. If f2 already exists, then it is overwritten by f1
(permissions permitting). If f1 is renamed, the method returns
true. Otherwise it returns false.
public String[] list() throws SecurityException
The list() method returns a String array
initialized to the names of each file in directory f.
It's useful for processing all the files in a directory.
public String[] list(FilenameFilter filter) throws
SecurityException
This is the same as the previous method except you can use a
FilenameFilter object (discussed in the next section) to restrict
which files are added to the list.
public boolean delete() throws
SecurityException
f.delete() tries to delete the file f.
This method returns true if the file existed and was
deleted. (You can't delete a file that doesn't exist). Otherwise it
returns false.