Under what circumstances could data just appear in a file?  Recall
that in many OSes, having an open file handle does not guarantee your
copy will know anything about what other jobs are doing.

Probably considered a less valuable enhancement and thus of lower
priority than providing a solution for sockets. On some operating
systems I suspect it requires a different code path to the sockets case.
Windows 9x doesn't support this functionality at all.

Mark Thornton

If you look at which classes have a register method to let them use
Selector logic:
DatagramChannel, Pipe.SinkChannel, Pipe.SourceChannel,
ServerSocketChannel, SocketChannel

These are all ones that could wait a second or more for something to
happen.  You don't want to tie up a thread (1 MB+ of RAM) that long
doing nothing.

In contrast, a FileChannel should satisfy its request within a few
milliseconds.  It is most efficient just to let the thread itself wait
for the i/o.

I am working on a companion to the File I/O Amanuensis for nio.  I
have not seen how you go about initiating two reads to a file on the
same thread then dealing with whichever completed first.  Somewhere in
my deep past, perhaps PL/I, I could do this.

In nio, it looks like you still need two threads and block on both.

       IIRC POSIX does not support selecting on files. Since POSIX is
       _probably_ the lowest common denominator that can be reasonably
       assumed for a JVM, if it doesn't it support you can't have it.

       m.