Package java.nio.file

Defines interfaces and classes for the Java virtual machine to access files, file attributes, and file systems.

See: Description

Interface Summary

Interface	Description
CopyOption	An object that configures how to copy or move a file.
DirectoryStream<T>	An object to iterate over the entries in a directory.
DirectoryStream.Filter<T>	An interface that is implemented by objects that decide if a directory entry should be accepted or filtered.
OpenOption	An object that configures how to open or create a file.
Path	An object that may be used to locate a file in a file system.

Class Summary

Class	Description
Files	This class consists exclusively of static methods that operate on files, directories, or other types of files.
FileStore	Storage for files.
FileSystem	Provides an interface to a file system and is the factory for objects to access files and other objects in the file system.
FileSystems	Factory methods for file systems.
Paths	This class consists exclusively of static methods that return a Path by converting a path string.

Enum Summary

Enum	Description
LinkOption	Defines the options as to how symbolic links are handled.
StandardCopyOption	Defines the standard copy options.
StandardOpenOption	Defines the standard open options.

Exception Summary

Exception	Description
AtomicMoveNotSupportedException	Checked exception thrown when a file cannot be moved as an atomic file system operation.
ClosedFileSystemException	Unchecked exception thrown when an attempt is made to invoke an operation on a file and the file system is closed.
DirectoryIteratorException	Runtime exception thrown if an I/O error is encountered when iterating over the entries in a directory.
DirectoryNotEmptyException	Checked exception thrown when a file system operation fails because a directory is not empty.
FileAlreadyExistsException	Checked exception thrown when an attempt is made to create a file or directory and a file of that name already exists.
FileSystemException	Thrown when a file system operation fails on one or two files.
InvalidPathException	Unchecked exception thrown when path string cannot be converted into a Path because the path string contains invalid characters, or the path string is invalid for other file system specific reasons.
NoSuchFileException	Checked exception thrown when an attempt is made to access a file that does not exist.
NotDirectoryException	Checked exception thrown when a file system operation, intended for a directory, fails because the file is not a directory.
ReadOnlyFileSystemException	Unchecked exception thrown when an attempt is made to update an object associated with a read-only FileSystem.

Package java.nio.file Description

Defines interfaces and classes for the Java virtual machine to access files, file attributes, and file systems.

The java.nio.file package defines classes to access files and file systems. The API to access file and file system attributes is defined in the java.nio.file.attribute package.

The following features of NIO are NOT supported by this subset:

• AttributeViews are not supported; basic attributes can be read or set
• Posix attributes are not supported
• DOS attributes are not supported
• Directory stream matching/globing is not supported
• Watching files is not supported
• File Locking is not supported
• ScatteringByteChannels and GatheringByteChannels are not supported
• Probing of content type is not supported
• FileSystemProviders are not supported; only the default provider is supported
• Symbolic links are not typically supported on the file systems provided by target devices:
  • If symbolic links are supported, the LinkOption.NOFOLLOW_LINKS behavior MUST be supported
  • Creation of hard or symbolic links is not supported
  • Reading of symbolic links is not supported

Minimal NIO File Implementation

The minimum implementation requires the default FileSystem with zero or more FileStores and zero or more RootDirectories.

Symbolic Links

Many operating systems and file systems support for symbolic links. A symbolic link is a special file that serves as a reference to another file. For the most part, symbolic links are transparent to applications and operations on symbolic links are automatically redirected to the target of the link. Exceptions to this are when a symbolic link is deleted or renamed/moved in which case the link is deleted or removed rather than the target of the link. This package includes support for symbolic links where implementations provide these semantics. File systems may support other types that are semantically close but support for these other types of links is not included in this package.

Visibility

The view of the files and file system provided by classes in this package are guaranteed to be consistent with other views provided by other instances in the same Java virtual machine. The view may or may not, however, be consistent with the view of the file system as seen by other concurrently running programs due to caching performed by the underlying operating system and delays induced by network-filesystem protocols. This is true regardless of the language in which these other programs are written, and whether they are running on the same machine or on some other machine. The exact nature of any such inconsistencies are system-dependent and are therefore unspecified.

Synchronized I/O File Integrity

The SYNC and DSYNC options are used when opening a file to require that updates to the file are written synchronously to the underlying storage device. In the case of the default filesystem, and the file resides on a local storage device, and the seekable channel is connected to a file that was opened with one of these options, then an invocation of the write method is only guaranteed to return when all changes made to the file by that invocation have been written to the device. These options are useful for ensuring that critical information is not lost in the event of a system crash.

General Exceptions

Unless otherwise noted, passing a null argument to a constructor or method of any class or interface in this package will cause a NullPointerException to be thrown. Additionally, invoking a method with a collection containing a null element will cause a NullPointerException, unless otherwise specified.

Unless otherwise noted, methods that attempt to access the file system will throw ClosedFileSystemException when invoked on objects associated with a FileSystem that has been closed. Additionally, any methods that attempt write access to a file system will throw ReadOnlyFileSystemException when invoked on an object associated with a FileSystem that only provides read-only access.

Optional Specific Exceptions

Most of the methods defined by classes in this package that access the file system specify that IOException be thrown when an I/O error occurs. In some cases, these methods define specific I/O exceptions for common cases. These exceptions, noted as optional specific exceptions, are thrown by the implementation where it can detect the specific error. Where the specific error cannot be detected then the more general IOException is thrown.

Since:

1.7, CLDC1.8