File	Doc	Category	Size	Date	Package
FileDescriptor.java	API Doc	Java SE 5 API	4228	Fri Aug 26 15:03:30 BST 2005	java.io

FileDescriptor

• java.lang.Object

Fields Summary
private int	fd
private long	handle
public static final FileDescriptor	in 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.
public static final FileDescriptor	out 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.
public static final FileDescriptor	err 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.

Constructors Summary
public FileDescriptor() Constructs an (invalid) FileDescriptor object. fd = -1; handle = -1;
private FileDescriptor(int fd) this.fd = fd; handle = -1;

Methods Summary
private static native void	initIDs()
private static native long	set(int d)
private static java.io.FileDescriptor	standardStream(int fd) FileDescriptor desc = new FileDescriptor(); desc.handle = set(fd); return desc;
public native void	sync() 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. exception SyncFailedException Thrown when the buffers cannot be flushed, or because the system cannot guarantee that all the buffers have been synchronized with physical media. since JDK1.1
public boolean	valid() Tests if this file descriptor object is valid. return true if the file descriptor object represents a valid, open file, socket, or other active I/O connection; false otherwise. return ((handle != -1) || (fd != -1));