22.26

java.io.FileDescriptor

THE PACKAGE JAVA.IO

22.26 The Class

java.io.FileDescriptor

A

FileDescriptor

 is an opaque representation of a connection to an actual file

in a file system, or to a network socket, or to another source or sink of bytes. The

main practical use for a file descriptor is to create a

FileInputStream

 ( 22.4.3)

or

FileOutputStream

 ( 22.16.3) to contain it.

public final class FileDescriptor {

public static final FileDescriptor in = ...;

public static final FileDescriptor out = ...;

public static final FileDescriptor err = ...;

public boolean valid();

}

22.26.1

public static final FileDescriptor in = ...

A file descriptor for the standard input stream. Usually, this file descriptor is not

used directly, but rather the input stream known as

System.in

 ( 20.18.1).

22.26.2

public static final FileDescriptor out = ...

A file descriptor for the standard output stream. Usually, this file descriptor is not

used directly, but rather the output stream known as

System.out

 ( 20.18.2).

22.26.3

public static final FileDescriptor err = ...

A file descriptor for the standard error output stream. Usually, this file descriptor

is not used directly, but rather the output stream known as

System.err

( 20.18.3).

22.26.4

public boolean valid()

If this

FileDescriptor

 is valid (represents an active connection to a file or other

active I/O connection), then the result is

true

. Otherwise, the result is

false

.

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