Thursday, September 10, 2009

The Path Class

The Path class, introduced in the JDK7 release, is the cornerstone of the java.nio.file package. If your application uses file I/O, you will want to learn about the powerful features of this class.

Version Note: If you have pre-JDK7 code that uses java.io.File, you can still take advantage of the Path class functionality by using the File.toPath method. See Legacy File I/O Code for more information.

As its name implies, the Path class is a programmatic representation of a path in the file system. A Path object contains the file name and directory list used to construct the path, and is used to examine, locate, and manipulate files.

A Path instance reflects the underlying platform. In the Solaris OS, a Path uses the Solaris syntax (/home/joe/foo) and in Microsoft Windows, a Path uses the Windows syntax (C:\home\joe\foo). A Path is not system independent. You cannot compare a Path from a Solaris file system and expect it to match a Path from a Windows file system, even if the directory structure is identical and both instances locate the same relative file.

The file or directory corresponding to the Path might not exist. You can create a Path instance and manipulate it in various ways: you can append to it, extract pieces of it, compare it to another path. At the appropriate time, you can check the existence of the file corresponding to the Path, create the file, open it, delete it, change its permissions, and so on.

The Path class is "link aware." Every Path method either detects what to do when a symbolic link is encountered, or it provides an option enabling you to configure the behavior when a symbolic link is encountered.

The Path class offers a rich feature set and is very easy to use. Most methods in the Path class fall into one of the following two categories:

  • Path operations – Methods for returning parts of a path, such as the root, name, or parent directory and methods for manipulating a path
  • File operations – Methods for opening a file for I/O, creating a file, creating a directory, deleting a file, copying a file, and so on

No comments: