=>      I'm a grad student at BYU who needs to write a hash table to
disk
=> at times and at other times read it back from disk.  My advisor
thinks
=> that the <nio> package might help me with that.  Class <FileChannel>
=> of that package looks promising; in fact it looks like its
=> <read( ByteBuffer dst, long position)> and
=> <write( ByteBuffer src, long position)> methods are precisely what I
=> need.  But they're both declared <abstract>, which means I have to
=> write a class that extends <FileChannel> and actually implements
those
=> two methods, doesn't it?
=
=No.  The standard API does it for you.  The classes that implement
those
=methods are not public, so they don't appear in the API documentation.
=You get the channel by calling getChannel on an object of one of the
=following three classes: FileInputStream, FileOutputStream, or
=RandomAccessFile.

    Chris, thanks, this worked just fine.  I was able to put a value
into a <ByteBuffer>, write it to a file, read it back from the file,
and verify that the value I originally put in actually came back in-
tact.

    Now I've got a different problem.  My advisor seems to think that
I should be able to take an arbitrary data structure (in my particular
case a complicated hash table), convert it to a <ByteBuffer>, and then
store that <ByteBuffer> to disk, in such a way that I can read the
data structure back later whenever I needed it.

    I tried to do this by converting a data structure to an <Object>
and then that <Object> to a <ByteBuffer> like so:

         sourceBb = (ByteBuffer) (Object) source;

But when I run this it throws a <ClassCastException> exception right
at this point in my code.  Am I taking the wrong approach?  Does any-
body know a way to convert an arbitrary data structure to a
<ByteBuffer>?  Any information you can give me on this would be great-
ly appreciated.

                               ---Kevin Simonson

"You'll never get to heaven, or even to LA,
if you don't believe there's a way."
from _Why Not_