The Java Files utility class

The Java java.nio.file.Files class provides a number of utility methods for performing basic operations such as loading, moving and copying files. The methods generally have the following features:

• they are generally static methods, with the first parameter being a Path object providing the location of the file in question;
• they throw exceptions (generally an IOException) to indicate when an error occors (whereas older Java I/O methods tended to return false or null, making it easy to forget to check for errors, and not necessarily indicating what the actual error was);
• they often allow relevant options to be set, such as whether file operations can replace existing data or whether the path in question follows symbolic links.

Exceptions thrown by Files methods generally include errors where the account running the Java program does not have relevant access permissions. This is generally more useful than older methods such as File.delete() which would simply fail silently and required the programmer to remember to check the return value (and often made it difficult if even possible to query the actual reason for the failure).

Some of the most useful methods of the Files are listed in the table below.

Method	Function	Comments
Files.isReadable() Files.isWritable() Files.isExecutable()	Checks the relevant access permissions on a given file.	These methods also check that the given file actually exists.
Files.copy()	Copies a source file to a given destination.	An attempt to copy over an existing file will fail unless StandardCopyOptions.REPLACE_EXISTING is passed in as an option.
Files.move()	Moves a source file to a given destination.	As with copy(), an attempt to move over an existing file will fail unless StandardCopyOptions.REPLACE_EXISTING is passed in.
Files.delete()	Deletes the given file.
Files.isSameFile()	Determines whether two given paths actually refer to the same file.	Given the presence of symbolic links or relative directory specifies (. and ..), two paths that are not strictly equal could actually refer to the same file. This method is used to detect such a case.

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