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# Class java.io.FileDescriptor

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

public final class FileDescriptor
extends Object

##

err
  Handle to standard error.
in
  Handle to standard input.
out
  Handle to standard output.

##

FileDescriptor()

##

sync()
  Force all system buffers to synchronize with the underlying device.
valid()
  Determines whether the file descriptor object is valid.

##

in

      public final static FileDescriptor in

  Handle to standard input.

out

      public final static FileDescriptor out

  Handle to standard output.

err

      public final static FileDescriptor err

  Handle to standard error.

##

FileDescriptor

      public FileDescriptor()

##

valid

      public boolean valid()

  Determines whether the file descriptor object is valid.

sync

      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 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.

  Throws: SyncFailedException
    Thrown when the buffers cannot be flushed, or because the system cannot guarantee that all the buffers have been synchronized with physical media.

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