chapter 9 ■ Java File I/O (NIO.2)

Summary

Working with the Path Class

•A Path object is a programming abstraction to represent a path of a file/directory.

•You can get an instance of Path using the get() method of the Paths class.

•Path provides two methods to use to compare Path objects: equals() and compareTo(). Even if two Path objects point to the same file/directory, it is not guaranteed that you will get true from the equals() method.

Performing Operations on Files/Directories

•You can check the existence of a file using the exists() method of the Files class.

•The Files class provides the methods isReadable(), isWriteable(), and isExecutable() to check the ability of the program to read, write, or execute programmatically.

•You can retrieve attributes of a file using the getAttributes() method.

•You can use the readAttributes() method of the Files class to read attributes of a file in bulk.

•The method copy() can be used to copy a file from one location to another. Similarly, the method move() can be used to move a file from one location to another.

•While copying, all the directories (except the last one if you are copying a directory) in the specified path must exist to avoid NoSuchFileException.

•Use the delete() method to delete a file; use the deleteIfExists() method to delete a file only if it exists.

Walking a File Tree

•The Files class provides two flavors of walkFileTree() to enable you to walk through a file system.

•The FileVisitor interface allows you to perform certain operations at certain key junctures.

•If you do not want to implement all four methods in the FileVisitor interface, you can simply extend your implementation from the SimpleFileVisitor class.

Finding a File

•The PathMatcher interface is useful when you want to find a file satisfying a certain pattern. You can specify the pattern using glob or regex.

Watching a Directory for Changes

•Java 7 offers a directory watch service that can notify you when the file you are working on is changed by some other program.

•You can register a Path object using a watch service along with certain event types. Whenever any file in the specified directory changes, an event is sent to the registered program.

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