Java Reference
In-Depth Information
3.
Write a program that copies all the files in one directory to another with the paths being entered from
the command line. The names of the file copies should have
_old
appended to them and no files in the
destination folder should be overwritten.
4.
Write a program that outputs a count of the total number of files in each directory in a file tree that is
specified by a path entered on the command line and outputs the total number of directories and files in
the tree. List the directories by name with each name followed by the file count in that directory.
• WHAT YOU LEARNED IN THIS CHAPTER
TOPIC
CONCEPT
File and
Directory
Paths
The
Path
class encapsulates a relative or absolute path to a file, a symbolic link, or a directory. The item
referenced by a
Path
object may or may not exist.
Accessing
Files and
Directories
The
Files
class provides methods that you can use to determine whether or not there is a physical file or
directory corresponding to the path that the object encapsulates.
Checking
for a File
or Direct-
ory
Having established that an entry corresponding to a
Path
object exists, you can determine whether the
entry is a file or directory by examining its attributes.
Accessing
Attributes
The attributes for an entry corresponding to a
Path
object can be obtained by calling the static
readBasicFileAttributes()
method, which is defined in the
Files
class. Attributes are returned as an
object of type
BasicFileAttributes
, and the
isDirectory()
and
isRegularFile()
methods for the ob-
ject enable you to determine whether the entry is a directory or a file. The
size()
attribute method returns
the size of a file in bytes.
Creating
Files and
Directories
The static
createFile()
or
createDirectory()
methods in the
Files
class can create a file or directory
for a
Path
object. The
createDirectory()
method only creates a single directory.
Creating a
Directory
Hierarchy
The static
createDirectories()
method in the
Files
class creates the directory specified by the
Path
ar-
gument and all necessary parent directories.
Accessing
the Entries
in a Dir-
ectory
The
newDirectoryStream()
method in the
Files
class returns a stream that contains all the entries in the
directory corresponding to a given Path object. You can supply a second argument to the
newDirect-
oryStream()
method that filters the entries so the stream only makes available a selected subset of the
entries.
Exploring
a File Tree
The static
walkFileTree()
method in the
Files
class initiates the process of walking a file tree that is
headed by a directory specified by a
Path
object. You receive information about the entries in the file tree
by implementing the methods specified in the
FileVisitor<Path>
interface.
