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java.io
public final class: FileDescriptor [javadoc | source]
java.lang.Object
   java.io.FileDescriptor
Instances of the file descriptor class serve as an opaque handle to the underlying machine-specific structure representing an open file, an open socket, or another source or sink of bytes. The main practical use for a file descriptor is to create a FileInputStream or FileOutputStream to contain it.

Applications should not create their own file descriptors.

Field Summary
public static final  FileDescriptor 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 {@code System.out}.
    Also see:
    java.lang.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 {@code System.err}.
    Also see:
    java.lang.System#err
 
Method from java.io.FileDescriptor Summary:
decrementAndGetUseCount,   incrementAndGetUseCount,   sync,   valid
Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from java.io.FileDescriptor Detail:
 int decrementAndGetUseCount() 
 int incrementAndGetUseCount() 
 public native  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.
 public boolean valid() 
    Tests if this file descriptor object is valid.