[JAVA] Unbuffered access to stdin

[Max Rabkin]

While java's System.in is, according to the javadocs, an InputStream, it
is in fact an instance of java.io.BufferedInputStream. Is there any way
to have unbuffered access to it without hacking the JRE? (I can do it on
my own computer, simply changing FilterInputStream's "in" field from
"protected" to "public", but then I can't distribute my program).

--Max

[Gordon Beaton]

On Sat, 05 Mar 2005 13:36:22 +0200, Max Rabkin wrote:

While java's System.in is, according to the javadocs, an InputStream, it
is in fact an instance of java.io.BufferedInputStream. Is there any way
to have unbuffered access to it without hacking the JRE? (I can do it on
my own computer, simply changing FilterInputStream's "in" field from
"protected" to "public", but then I can't distribute my program).

AFAIK no.

However if you said why you think you need to do this, maybe someone
could suggest an alternative solution.

/gordon

--
[ do not email me copies of your followups ]
g o r d o n + n e w s @ b a l d e r 1 3 . s e

[Max]

Gordon Beaton wrote:

On Sat, 05 Mar 2005 13:36:22 +0200, Max Rabkin wrote:

[unbuffered access to System.in]
However if you said why you think you need to do this, maybe someone
could suggest an alternative solution.

I am writing an interpreter for an esoteric language (in the vein of
BrainF***). The only input instruction is read-byte-to-stack.
/gordon

[Gordon Beaton]

On Sat, 05 Mar 2005 21:05:44 +0200, Max wrote:

I am writing an interpreter for an esoteric language (in the vein of
BrainF***). The only input instruction is read-byte-to-stack.

I'll interpret that to mean that you want to be able to read from
System.in without waiting for the user to press enter - is that right?
If so, it's your OS console, not Java's buffering of System.in that
prevents it, and consequently unbuffering System.in (alone) won't let
you do it.

You *can* read individual bytes from System.in without waiting for
enter. Try piping input from a file or other source to see that it's
possible.

On unix-like platforms, you can use "stty -icanon min 1" to change
console mode so you can do character-at-a-time input. On other
operating systems, I have no idea.

/gordon

--
[ do not email me copies of your followups ]
g o r d o n + n e w s @ b a l d e r 1 3 . s e

[Max]

Gordon Beaton wrote:

You *can* read individual bytes from System.in without waiting for
enter. Try piping input from a file or other source to see that it's
possible.

How? With System.in.read()? Ok. Since that didn't work, I thought it was
Java's fault.
On unix-like platforms, you can use "stty -icanon min 1" to change
console mode so you can do character-at-a-time input. On other
operating systems, I have no idea.
Thanks. I'm currently not running a unix-like platform. Other users of
my computer complain too much if they don't have windows, and last time
a tried a dual-boot setup, my windows died. :(
/gordon

[Ted Dunning]

Don't use standard input, then. Build a simple gui where you receive
key down events directly. Then you can do anything you want.