Files, Streams and Object Serialization - Java: How to Program Early Objects - page 648

Getting Path Objects from URIs
An overloaded version of Files static method get uses a URI object to locate the file or
directory. A Uniform Resource Identifier (URI) is a more general form of the Uniform
Resource Locators (URLs) that are used to locate websites. For example, the URL http:/
/www.deitel.com/ is the URL for the Deitel & Associates website. URIs for locating files
vary across operating systems. On Windows platforms, the URI
file://C:/data.txt
identifies the file data.txt stored in the root directory of the C: drive. On UNIX/Linux
platforms, the URI
file:/home/student/data.txt
identifies the file data.txt stored in the home directory of the user student .
Example: Getting File and Directory Information
Figure 15.2 prompts the user to enter a file or directory name, then uses classes Paths ,
Path , Files and DirectoryStream to output information about that file or directory.The
program begins by prompting the user for a file or directory (line 16). Line 19 inputs the
filename or directory name and passes it to Paths static method get , which converts the
String to a Path . Line 21 invokes Files static method exists , which receives a Path
and determines whether it exists (either as a file or as a directory) on disk. If the name does
not exist, control proceeds to line 49, which displays a message containing the Path 's
String representation followed by “ does not exist .” Otherwise, lines 24-45 execute:
• Path method getFileName (line 24) gets the String name of the file or directory
without any location information.
• Files static method isDirectory (line 26) receives a Path and returns a bool-
ean indicating whether that Path represents a directory on disk.
• Path method isAbsolute (line 28) returns a boolean indicating whether that
Path represents an absolute path to a file or directory.
• Files static method getLastModifiedTime (line 30) receives a Path and returns
a FileTime (package java.nio.file.attribute ) indicating when the file was last
modified. The program outputs the FileTime 's default String representation.
• Files static method size (line 31) receives a Path and returns a long represent-
ing the number of bytes in the file or directory. For directories, the value returned
is platform specific.
• Path method toString (called implicitly at line 32) returns a String represent-
ing the Path .
• Path method toAbsolutePath (line 33) converts the Path on which it's called to
an absolute path.
If the Path represents a directory (line 35), lines 40-41 use Files static method new-
DirectoryStream (lines 40-41) to get a DirectoryStream<Path> containing Path objects
for the directory's contents. Lines 43-44 display the String representation of each Path
in the DirectoryStream<Path> . Note that DirectoryStream is a generic type like Array-
List (Section 7.16).