Re: Read a single byte from stdin

Tom Anderson <>
Mon, 13 Jul 2009 23:56:23 +0100
On Mon, 13 Jul 2009, Martin Gregorie wrote:

On Mon, 13 Jul 2009 03:49:35 -0700, Roedy Green wrote:

Peter van der Linden wrote a class that fielded keystroke events to
simulate a console that could read a character at a time. I vaguely
recall perusing the code and thinking it was quite a bit terser than I

Earlier today I was wondering how possible it would be to do exactly that
via the KeyEvent mechanism.

It seems likely that I'll have to define an invisible AWT or Swing window
the same size as my screen in order to define the area where key presses
would generate KeyEvents. The idea is that this whole mess should run on
a headless server that's being accessed via ssh, so does anybody know if
a program that creates invisible AWT or Swing objects can start correctly
on a headless system that doesn't have either an X-server running locally
or access to a remote X-term via ssh X.11 forwarding?

Nope. And if it did, it wouldn't do what you want - those key events can
only come from X, so if there's no X, there are no key events.

I'd look for a java wrapper round curses/ncurses - you're talking about "a
headless machine" here, which suggests that there's a particular machine
in mind and portability isn't a requirement here. Alternatively, a C
driver program that reads a character at a time (perhaps using the POSIX
incantation someone posted already) and passes it to java.

Or, how about making your app use a socket, then connecting to it with
telnet? It's a bit Heath Robinson, but i think that should give you a
character at a time, provided your telnet is cooperative.


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hasn't started yet. -- Alan Kay

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