OpenJDK 1.22 · java.io.FileDescriptor · APIdia, the JavaDoc alternative

Modifier and Type	Field and Description
private boolean	append true, if file is opened for appending.
private PhantomCleanable<FileDescriptor>	cleanup Cleanup in case FileDescriptor is not explicitly closed.
private boolean	closed
public static final FileDescriptor	err A handle to the standard error stream.
private int	fd
private long	handle
public static final FileDescriptor	in A handle to the standard input stream.
private List<Closeable>	otherParents
public static final FileDescriptor	out A handle to the standard output stream.
private Closeable	parent

Access	Constructor and Description
public	FileDescriptor() Constructs an (invalid) FileDescriptor object.
private	FileDescriptor(int the raw fd number (0, 1, 2) fd) Used for standard input, output, and error only.

Method Summary

Modifier and Type	Method and Description
pack-priv synchronized void	attach(Closeable c) Attach a Closeable to this FD for tracking.
pack-priv synchronized void	close() Close the raw file descriptor or handle, if it has not already been closed.
private native void	close0()
pack-priv synchronized void	closeAll(Closeable releaser) Cycle through all Closeables sharing this FD and call close() on each one.
private static native boolean	getAppend(int fd) Returns true, if the file was opened for appending.
private static native long	getHandle(int d)
private static native void	initIDs()
pack-priv synchronized void	registerCleanup(PhantomCleanable<FileDescriptor> a PhantomCleanable to register cleanable) Register a cleanup for the current handle.
pack-priv synchronized void	set(int the raw fd or -1 to indicate closed fd) Set the fd.
pack-priv void	setHandle(long the handle or -1 to indicate closed handle) Set the handle.
public void	sync() Force all system buffers to synchronize with the underlying device.
private native void	sync0()
pack-priv synchronized void	unregisterCleanup() Unregister a cleanup for the current raw fd or handle.
public boolean	Returns: `true` if the file descriptor object represents a valid, open file, socket, or other active I/O connection; `false` otherwise. valid() Tests if this file descriptor object is valid.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

append	back to summary
private boolean append true, if file is opened for appending.

cleanup	back to summary
private PhantomCleanable<FileDescriptor> cleanup Cleanup in case FileDescriptor is not explicitly closed.

closed	back to summary
private boolean closed

err back to summary

err	back to summary
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`. See Also `java.lang.System#err`

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.

See Also: java.lang.System#err

fd	back to summary
private int fd

handle	back to summary
private long handle

in back to summary

in	back to summary
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`. See Also `java.lang.System#in`

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.

See Also: java.lang.System#in

otherParents	back to summary
private List<Closeable> otherParents

out back to summary

out	back to summary
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`. See Also `java.lang.System#out`

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.

See Also: java.lang.System#out

parent	back to summary
private Closeable parent

Constructor Detail

FileDescriptor	back to summary
public FileDescriptor() Constructs an (invalid) FileDescriptor object. The fd or handle is set later.

FileDescriptor	back to summary
private FileDescriptor(int fd) Used for standard input, output, and error only. For Windows the corresponding handle is initialized. For Unix the append mode is cached. Parameters fd:int the raw fd number (0, 1, 2)

FileDescriptor

back to summary

private FileDescriptor(int fd)

Used for standard input, output, and error only. For Windows the corresponding handle is initialized. For Unix the append mode is cached.

Parameters

fd:int: the raw fd number (0, 1, 2)

Method Detail

attach	back to summary
pack-priv synchronized void attach(Closeable c) Attach a Closeable to this FD for tracking. parent reference is added to otherParents when needed to make closeAll simpler.

close	back to summary
pack-priv synchronized void close() throws IOException Close the raw file descriptor or handle, if it has not already been closed. The native code sets the fd and handle to -1. Clear the cleaner so the close does not happen twice. Package private to allow it to be used in java.io. Exceptions IOException: if close fails

back to summary

pack-priv synchronized void close() throws IOException

Close the raw file descriptor or handle, if it has not already been closed. The native code sets the fd and handle to -1. Clear the cleaner so the close does not happen twice. Package private to allow it to be used in java.io.

Exceptions

IOException:: if close fails

close0	back to summary
private native void close0() throws IOException

closeAll	back to summary
pack-priv synchronized void closeAll(Closeable releaser) throws IOException Cycle through all Closeables sharing this FD and call close() on each one. The caller closeable gets to call close0(). Annotations @SuppressWarnings:try

closeAll

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pack-priv synchronized void closeAll(Closeable releaser) throws IOException

Cycle through all Closeables sharing this FD and call close() on each one. The caller closeable gets to call close0().

Annotations

@SuppressWarnings:try

getAppend	back to summary
private static native boolean getAppend(int fd) Returns true, if the file was opened for appending.

getHandle	back to summary
private static native long getHandle(int d)

initIDs	back to summary
private static native void initIDs()

registerCleanup	back to summary
pack-priv synchronized void registerCleanup(PhantomCleanable<FileDescriptor> cleanable) Register a cleanup for the current handle. Used directly in java.io and indirectly via fdAccess. The cleanup should be registered after the handle is set in the FileDescriptor. Parameters cleanable:PhantomCleanable<FileDescriptor> a PhantomCleanable to register

registerCleanup

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pack-priv synchronized void registerCleanup(PhantomCleanable<FileDescriptor> cleanable)

Register a cleanup for the current handle. Used directly in java.io and indirectly via fdAccess. The cleanup should be registered after the handle is set in the FileDescriptor.

Parameters

cleanable:PhantomCleanable<FileDescriptor>: a PhantomCleanable to register

set back to summary

set	back to summary
pack-priv synchronized void set(int fd) Set the fd. Used on Unix and for sockets on Windows and Unix. If setting to -1, clear the cleaner. The `registerCleanup` method should be called for new fds. Parameters fd:int the raw fd or -1 to indicate closed

pack-priv synchronized void set(int fd)

Set the fd. Used on Unix and for sockets on Windows and Unix. If setting to -1, clear the cleaner. The registerCleanup method should be called for new fds.

Parameters

fd:int: the raw fd or -1 to indicate closed

setHandle back to summary

setHandle	back to summary
pack-priv void setHandle(long handle) Set the handle. Used on Windows for regular files. If setting to -1, clear the cleaner. The `registerCleanup` method should be called for new handles. Parameters handle:long the handle or -1 to indicate closed

pack-priv void setHandle(long handle)

Set the handle. Used on Windows for regular files. If setting to -1, clear the cleaner. The registerCleanup method should be called for new handles.

Parameters

handle:long: the handle or -1 to indicate closed

sync	back to summary
public void sync() throws SyncFailedException 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 FileDescriptor 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. Exceptions 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 1.1

sync

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public void sync() throws SyncFailedException

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 FileDescriptor 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.

Exceptions

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

1.1

sync0	back to summary
private native void sync0() throws SyncFailedException

unregisterCleanup back to summary

unregisterCleanup	back to summary
pack-priv synchronized void unregisterCleanup() Unregister a cleanup for the current raw fd or handle. Used directly in java.io and indirectly via fdAccess. Normally `close()` should be used except in cases where it is certain the caller will close the raw fd and the cleanup must not close the raw fd. `unregisterCleanup()` must be called before the raw fd is closed to prevent a race that makes it possible for the fd to be reallocated to another use and later the cleanup might be invoked.

pack-priv synchronized void unregisterCleanup()

Unregister a cleanup for the current raw fd or handle. Used directly in java.io and indirectly via fdAccess. Normally close() should be used except in cases where it is certain the caller will close the raw fd and the cleanup must not close the raw fd. unregisterCleanup() must be called before the raw fd is closed to prevent a race that makes it possible for the fd to be reallocated to another use and later the cleanup might be invoked.

valid back to summary

valid	back to summary
public boolean valid() Tests if this file descriptor object is valid. Returns:boolean `true` if the file descriptor object represents a valid, open file, socket, or other active I/O connection; `false` otherwise.

public boolean valid()

Tests if this file descriptor object is valid.

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

public final Class FileDescriptor

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail