java.io
Class FileDescriptor

java.lang.Object
  |
  +--java.io.FileDescriptor

public final class FileDescriptor

extends Object

Untamed:

Field Summary

static FileDescriptor	err Enabled: A handle to the standard error stream.
private int	fd
static FileDescriptor	in Enabled: A handle to the standard input stream.
static FileDescriptor	out Enabled: A handle to the standard output stream.

Constructor Summary

	FileDescriptor() Enabled: Constructs an (invalid) FileDescriptor object.
private	FileDescriptor(int fd)

Method Summary

private static void	initIDs()
void	sync() Enabled: Force all system buffers to synchronize with the underlying device.
boolean	valid() Enabled: Tests if this file descriptor object is valid.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

fd

private int fd

in

public static final FileDescriptor in

Enabled: A handle to the standard input stream. Usually, this file descriptor is not used directly, but rather via the input stream known as System.in.

See Also:

java.lang.System#in

out

public static final FileDescriptor out

Enabled: A handle to the standard output stream. Usually, this file descriptor is not used directly, but rather via the output stream known as System.out.

See Also:

java.lang.System#out

err

public static final FileDescriptor err

Enabled: A handle to the standard error stream. Usually, this file descriptor is not used directly, but rather via the output stream known as System.err.

See Also:

java.lang.System#err

Constructor Detail

FileDescriptor

public FileDescriptor()

Enabled: Constructs an (invalid) FileDescriptor object.

FileDescriptor

private FileDescriptor(int fd)

Method Detail

valid

public boolean valid()

Enabled: Tests if this file descriptor object is valid.

Returns:

true if the file descriptor object represents a valid, open file, socket, or other active I/O connection; false otherwise.

sync

public void sync()
          throws SyncFailedException

Enabled: Force all system buffers to synchronize with the underlying device. This method returns after all modified data and attributes of this FileDescriptor have been written to the relevant device(s). In particular, if this FileDescriptor refers to a physical storage medium, such as a file in a file system, sync will not return until all in-memory modified copies of buffers associated with this FileDesecriptor have been written to the physical medium. sync is meant to be used by code that requires physical storage (such as a file) to be in a known state For example, a class that provided a simple transaction facility might use sync to ensure that all changes to a file caused by a given transaction were recorded on a storage medium. sync only affects buffers downstream of this FileDescriptor. If any in-memory buffering is being done by the application (for example, by a BufferedOutputStream object), those buffers must be flushed into the FileDescriptor (for example, by invoking OutputStream.flush) before that data will be affected by sync.

SyncFailedException

Since:

JDK1.1

initIDs

private static void initIDs()