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
package is used by service provider implementors wishing to extend the
platform default provider, or to construct other provider implementations.
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.
File class defines the
toPath method to construct a
Path by converting
the abstract path represented by the
java.io.File object. The resulting
Path can be used to operate on the same file as the
Path specification provides further information
on the interoperability between
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.
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 provider, 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
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. If the file does not reside on a local device then no such guarantee
is made. Whether this guarantee is possible with other
provider implementations is provider
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 an array or collection containing a
will cause a
NullPointerException, unless otherwise specified.
Unless otherwise noted, methods that attempt to access the file system
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
FileSystem that only provides read-only
Unless otherwise noted, invoking a method of any class or interface in
this package created by one
provider with a parameter that is an object created by another provider,
Optional Specific ExceptionsMost of the methods defined by classes in this package that access the file system specify that
IOExceptionbe 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
Interface Summary Interface Description CopyOptionAn 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. FileVisitor<T>A visitor of files. OpenOptionAn object that configures how to open or create a file. PathAn object that may be used to locate a file in a file system. PathMatcherAn interface that is implemented by objects that perform match operations on paths. SecureDirectoryStream<T>A
DirectoryStreamthat defines operations on files that are located relative to an open directory.
WatchableAn object that may be registered with a watch service so that it can be watched for changes and events. WatchEvent<T>An event or a repeated event for an object that is registered with a
WatchEvent.Kind<T>An event kind, for the purposes of identification. WatchEvent.Modifier WatchKey WatchServiceA watch service that watches registered objects for changes and events.
Class Summary Class Description FilesThis class consists exclusively of static methods that operate on files, directories, or other types of files. FileStoreStorage for files. FileSystemProvides an interface to a file system and is the factory for objects to access files and other objects in the file system. FileSystemsFactory methods for file systems. LinkPermissionThe
Permissionclass for link creation operations.
Paths SimpleFileVisitor<T>A simple visitor of files with default behavior to visit all files and to re-throw I/O errors. StandardWatchEventKindsDefines the standard event kinds.
Enum Summary Enum Description AccessModeDefines access modes used to test the accessibility of a file. FileVisitOptionDefines the file tree traversal options. FileVisitResultThe result type of a
LinkOptionDefines the options as to how symbolic links are handled. StandardCopyOptionDefines the standard copy options. StandardOpenOptionDefines the standard open options.
Exception Summary Exception Description AccessDeniedExceptionChecked exception thrown when a file system operation is denied, typically due to a file permission or other access check. AtomicMoveNotSupportedExceptionChecked exception thrown when a file cannot be moved as an atomic file system operation. ClosedDirectoryStreamExceptionUnchecked exception thrown when an attempt is made to invoke an operation on a directory stream that is closed. ClosedFileSystemExceptionUnchecked exception thrown when an attempt is made to invoke an operation on a file and the file system is closed. ClosedWatchServiceExceptionUnchecked exception thrown when an attempt is made to invoke an operation on a watch service that is closed. DirectoryIteratorExceptionRuntime exception thrown if an I/O error is encountered when iterating over the entries in a directory. DirectoryNotEmptyExceptionChecked exception thrown when a file system operation fails because a directory is not empty. FileAlreadyExistsExceptionChecked exception thrown when an attempt is made to create a file or directory and a file of that name already exists. FileSystemAlreadyExistsExceptionRuntime exception thrown when an attempt is made to create a file system that already exists. FileSystemExceptionThrown when a file system operation fails on one or two files. FileSystemLoopExceptionChecked exception thrown when a file system loop, or cycle, is encountered. FileSystemNotFoundExceptionRuntime exception thrown when a file system cannot be found. InvalidPathExceptionUnchecked exception thrown when path string cannot be converted into a
Pathbecause the path string contains invalid characters, or the path string is invalid for other file system specific reasons.
NoSuchFileExceptionChecked exception thrown when an attempt is made to access a file that does not exist. NotDirectoryExceptionChecked exception thrown when a file system operation, intended for a directory, fails because the file is not a directory. NotLinkExceptionChecked exception thrown when a file system operation fails because a file is not a symbolic link. ProviderMismatchExceptionUnchecked exception thrown when an attempt is made to invoke a method on an object created by one file system provider with a parameter created by a different file system provider. ProviderNotFoundExceptionRuntime exception thrown when a provider of the required type cannot be found. ReadOnlyFileSystemExceptionUnchecked exception thrown when an attempt is made to update an object associated with a