Accessing Files and Directories - Beginning Java - page 414

Obtaining File Attributes
To determine whether a Path object references a file or a directory, you can use the static isDirectory()
and isRegularFile() methods in the Files class. With both methods the first argument is the Path object
you are interested in. You can specify NOFOLLOW_LINKS as the optional second argument if you do not want
links to be followed.
You can also query the attributes of a file by calling the static readAttributes() method that is defined
in the Files class with the Path object specifying the file:
try{
BasicFileAttributes attr = Files.readAttributes(path,
BasicFileAttributes.class);
}catch(IOException e) {
System.err.println(e);

}

The second argument to the method is the class type for the attributes you require. Here, the attributes
are returned as a reference to an object of type BasicFileAttributes that contains attributes common
to most file systems. You also have the possibility of being more specific by specifying PosixFilesAt-
tributes.class or DosFileAttributes.class . All these are interface types defined in the
java.nio.file.attribute package. You can optionally specify NOFOLLOW_LINKS as the third argument if
you do not want symbolic links to be followed. The method throws an UnsupportedOperationException
if the attributes type is not supported and an IOException if an I/O error occurs.
The BasicFilesAttributes interface defines the methods shown in Table 9-4 that you can use to get
information about a directory or file path:

TABLE 9-4 : BasicFilesAttributes Methods that Retrieve Directory or Path Information
METHODS DESCRIPTION
isDirectory() Returns true if the path references a directory.
isRegularFile() Returns true if the path references a regular file.
isSymbolicLink() Returns true if the path references a symbolic link.
isOther() Returns true if the path references something other than a regular file, a directory, or a sym-
bolic link.
creationTime() Returns a FileTime object specifying the time the file was created.
lastAccessTime() Returns a FileTime object specifying the time the file was last accessed.
lastModifiedTime() Returns a FileTime object specifying the time the file was last modified.
size() Returns the size of the file in bytes as a value of type long .

Returns a reference of type Object to a key that uniquely identifies the file or null if a key is
not available.

fileKey()

A java.nio.file.attribute.FileTime object is a timestamp value for a file. You can use its
toString() method to get a string representation of its value.
To see how some of these methods go together, you can try a simple example.

TRY IT OUT: Testing a Path for a File or Directory
Try the following source code: