java.io
Class FileDescriptor

java.lang.Object
  java.io.FileDescriptor

public final class FileDescriptor
extends Object

FileDescriptor is the lowest level representation of a File, Device, or Socket. You can create any of the IO classes which take a FileDescriptor as an argument by querying an open Socket or File for the FileDescriptor.

The FileDescriptor class also contains static fields representing Standard Input, Output and Error. You can use these directly if desired but it is recommended you go through System.in, System.out, and System.err streams respectively.

Applications should not create new FileDescriptors.

See Also:

FileInputStream.getFD(), FileOutputStream.getFD(), RandomAccessFile.getFD()

Field Summary

static FileDescriptor	err FileDescriptor representing Standard Error
static FileDescriptor	in FileDescriptor representing Standard In
static FileDescriptor	out FileDescriptor representing Standard Out

Constructor Summary

FileDescriptor()
Constructs a new FileDescriptor containing an invalid handle.

Method Summary

void	sync() Ensures that data which is buffered within the underlying implementation is written out to the appropriate device before returning.
boolean	valid() Answers a boolean indicating whether or not this FileDescriptor is valid.

Methods inherited from class java.lang.Object

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

Field Detail

in

public static final FileDescriptor in

FileDescriptor representing Standard In

out

public static final FileDescriptor out

FileDescriptor representing Standard Out

err

public static final FileDescriptor err

FileDescriptor representing Standard Error

Constructor Detail

FileDescriptor

public FileDescriptor()

Constructs a new FileDescriptor containing an invalid handle. This constructor does nothing interesting. Provided for signature compatibility.

Method Detail

sync

public void sync()
          throws SyncFailedException

Ensures that data which is buffered within the underlying implementation is written out to the appropriate device before returning.

Throws:

SyncFailedException - when the operation fails

valid

public boolean valid()

Answers a boolean indicating whether or not this FileDescriptor is valid.

Returns:

true if this FileDescriptor is valid, false otherwise