File I/O (Featuring NIO.2)

Note: This tutorial reflects the file I/O mechanism introduced in the JDK 7 release. The Java SE 6 version of the File I/O tutorial was brief, but you can download the Java SE Tutorial 2008-03-14 version of the tutorial which contains the earlier File I/O content.

The java.nio.file package and its related package, java.nio.file.attribute, provide comprehensive support for file I/O and for accessing the default file system. Though the API has many classes, you need to focus on only a few entry points. You will see that this API is very intuitive and easy to use.

The tutorial starts by asking what is a path? Then, the Path class, the primary entry point for the package, is introduced. Methods in the Path class relating to syntactic operations are explained. The tutorial then moves on to the other primary class in the package, the Files class, which contains methods that deal with file operations. First, some concepts common to many file operations are introduced. The tutorial then covers methods for checking, deleting, copying, and moving files.

The tutorial shows how metadata is managed, before moving on to file I/O and directory I/O. Random access files are explained and issues specific to symbolic and hard links are examined.

Next, some of the very powerful, but more advanced, topics are covered. First, the capability to recursively walk the file tree is demonstrated, followed by information about how to search for files using wild cards. Next, how to watch a directory for changes is explained and demonstrated. Then, methods that didn't fit elsewhere are given some attention.

Finally, if you have file I/O code written prior to the Java SE 7 release, there is a map from the old API to the new API, as well as important information about the File.toPath method for developers who would like to leverage the new API without rewriting existing code.