Legacy File I/O Code
Trail: Essential Classes
Lesson: Basic I/O
Section: File I/O (Featuring NIO.2)

Legacy File I/O Code

Interoperability With Legacy Code

Prior to the Java SE 7 release, the class was the mechanism used for file I/O, but it had several drawbacks.

Perhaps you have legacy code that uses and would like to take advantage of the java.nio.file.Path functionality with minimal impact to your code.

The class provides the toPath method, which converts an old style File instance to a java.nio.file.Path instance, as follows:

Path input = file.toPath();

You can then take advantage of the rich feature set available to the Path class.

For example, assume you had some code that deleted a file:


You could modify this code to use the Files.delete method, as follows:

Path fp = file.toPath();

Conversely, the Path.toFile method constructs a object for a Path object.

Mapping Functionality to java.nio.file

Because the Java implementation of file I/O has been completely re-architected in the Java SE 7 release, you cannot swap one method for another method. If you want to use the rich functionality offered by the java.nio.file package, your easiest solution is to use the File.toPath method as suggested in the previous section. However, if you do not want to use that approach or it is not sufficient for your needs, you must rewrite your file I/O code.

There is no one-to-one correspondence between the two APIs, but the following table gives you a general idea of what functionality in the API maps to in the java.nio.file API and tells you where you can obtain more information. Functionality java.nio.file Functionality Tutorial Coverage java.nio.file.Path The Path Class The SeekableByteChannel functionality. Random Access Files
File.canRead, canWrite, canExecute Files.isReadable, Files.isWritable, and Files.isExecutable.
On UNIX file systems, the Managing Metadata (File and File Store Attributes) package is used to check the nine file permissions.
Checking a File or Directory
Managing Metadata
File.isDirectory(), File.isFile(), and File.length() Files.isDirectory(Path, LinkOption...), Files.isRegularFile(Path, LinkOption...), and Files.size(Path) Managing Metadata
File.lastModified() and File.setLastModified(long) Files.getLastModifiedTime(Path, LinkOption...) and Files.setLastMOdifiedTime(Path, FileTime) Managing Metadata
The File methods that set various attributes: setExecutable, setReadable, setReadOnly, setWritable These methods are replaced by the Files method setAttribute(Path, String, Object, LinkOption...). Managing Metadata
new File(parent, "newfile") parent.resolve("newfile") Path Operations
File.renameTo Files.move Moving a File or Directory
File.delete Files.delete Deleting a File or Directory
File.createNewFile Files.createFile Creating Files
File.deleteOnExit Replaced by the DELETE_ON_CLOSE option specified in the createFile method. Creating Files
File.createTempFile Files.createTempFile(Path, String, FileAttributes<?>), Files.createTempFile(Path, String, String, FileAttributes<?>) Creating Files
Creating and Writing a File by Using Stream I/O
Reading and Writing Files by Using Channel I/O
File.exists Files.exists and Files.notExists Verifying the Existence of a File or Directory
File.compareTo and equals Path.compareTo and equals Comparing Two Paths
File.getAbsolutePath and getAbsoluteFile Path.toAbsolutePath Converting a Path
File.getCanonicalPath and getCanonicalFile Path.toRealPath or normalize Converting a Path (toRealPath)
Removing Redundancies From a Path (normalize)
File.toURI Path.toURI Converting a Path
File.isHidden Files.isHidden Retrieving Information About the Path
File.list and listFiles Path.newDirectoryStream Listing a Directory's Contents
File.mkdir and mkdirs Path.createDirectory Creating a Directory
File.listRoots FileSystem.getRootDirectories Listing a File System's Root Directories
File.getTotalSpace, File.getFreeSpace, File.getUsableSpace FileStore.getTotalSpace, FileStore.getUnallocatedSpace, FileStore.getUsableSpace, FileStore.getTotalSpace File Store Attributes

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