File Methods

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.

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Copyright 1997, 2000, 2006 Elliotte Rusty Harold
Last Modified August 22, 2006