Java Reference
In-Depth Information
File , which also is part of the java.io package, represents a file or folder reference. The
following File constructors can be used:
File( String ) —Creates a File object with the specified folder; no filename is
indicated, so this refers only to a file folder.
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File( String , String ) —Creates a File object with the specified folder path and
the specified name.
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File( File , String ) —Creates a File object with its path represented by the spec-
ified File and its name indicated by the specified String .
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You can call several useful methods on a File object.
The exists() method returns a Boolean value indicating whether the file exists under
the name and folder path established when the File object was created. If the file exists,
you can use the length() method to return a long integer indicating the size of the file
in bytes.
The renameTo( File ) method renames the file to the name specified by the File argu-
ment. A Boolean value is returned, indicating whether the operation was successful.
The delete() or deleteOnExit() method should be called to delete a file or a folder.
The delete() method attempts an immediate deletion (returning a Boolean value indi-
cating whether it worked). The deleteOnExit() method waits to attempt deletion until
the rest of the program has finished running. This method does not return a value—you
couldn't do anything with the information—and the program must finish at some point
for it to work.
The getName() and getPath() methods return strings containing the name and path of
the file.
Several methods are useful when the File object represents a folder rather than a file.
The mkdir() method can be used to create the folder specified by the File object it is
called on. It returns a Boolean value indicating success or failure. There is no compara-
ble method to remove folders— delete() can be used on folders as well as files.
The isDirectory() method returns the Boolean value true when the File object is a
folder and false otherwise.
The listFiles() method returns an array of File objects representing the contents of
the folder—all its files and subfolders.
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