Java Reference
In-Depth Information
Character-based input and output can be performed with classes
Scanner
and
For-
matter
, as you'll see in Section 15.4. You've used class
Scanner
extensively to input data
from the keyboard.
Scanner
also can read data from a file. Class
Formatter
enables for-
matted data to be output to any text-based stream in a manner similar to method
System.out.printf
. Appendix I presents the details of formatted output with
printf
. All
these features can be used to format text files as well. In Chapter 28, we use stream classes
to implement networking applications.
Java SE 8 Adds Another Type of Stream
Chapter 17, Java SE 8 Lambdas and Streams, introduces a new type of stream that's used
to process collections of elements (like arrays and
ArrayList
s), rather than the streams of
bytes we discuss in this chapter's file-processing examples.
Directory Information
Interfaces
Path
and
DirectoryStream
and classes
Paths
and
Files
(all from package
ja-
va.nio.file
) are useful for retrieving information about files and directories on disk:
•
Path
interface—Objects of classes that implement this interface represent the lo-
cation of a file or directory.
Path
objects do not open files or provide any file-pro-
cessing capabilities.
•
Paths
class—Provides
static
methods used to get a
Path
object representing a
file or directory location.
•
Files
class—Provides
static
methods for common file and directory manipu-
lations, such as copying files; creating and deleting files and directories; getting
information about files and directories; reading the contents of files; getting ob-
jects that allow you to manipulate the contents of files and directories; and more
•
DirectoryStream
interface—Objects of classes that implement this interface en-
able a program to iterate through the contents of a directory.
Creating
Path
Objects
You'll use class
static
method
get
of class
Paths
to convert a
String
representing a file's
or directory's location into a
Path
object. You can then use the methods of interface
Path
and class
Files
to determine information about the specified file or directory. We discuss
several such methods momentarily. For complete lists of their methods, visit:
Absolute vs. Relative Paths
A file or directory's path specifies its location on disk. The path includes some or all of the
directories leading to the file or directory. An
absolute path
contains
all
directories, start-
ing with the
root directory
, that lead to a specific file or directory. Every file or directory
on a particular disk drive has the
same
root directory in its path. A
relative path
is “relative”
to another directory—for example, a path relative to the directory in which the application
began executing.
