[Rxtx] Underlying input stream returned zero bytes

[Trent Jarvi]

On Thu, 21 Sep 2006, TEIXOEIRA at terra.es wrote:

>
> Hi, there.
> I'm having difficulties reading a serial line with RXTX 2.1-7 on Windows XP, I can communicate through this serial line using
> HiperTerminal though.
> Also, I can't find any clues about this issue on the internet. Can anybody tell what might cause this exception while reading?
>
> Kind regards.
>
> java.io.IOException: Underlying input stream returned zero bytes
>        at sun.nio.cs.StreamDecoder$CharsetSD.readBytes(StreamDecoder.java:415)
>        at sun.nio.cs.StreamDecoder$CharsetSD.implRead(StreamDecoder.java:453)
>        at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:183)
>        at java.io.InputStreamReader.read(InputStreamReader.java:167)
>        at java.io.BufferedReader.fill(BufferedReader.java:136)
>        at java.io.BufferedReader.readLine(BufferedReader.java:299)
>        at java.io.BufferedReader.readLine(BufferedReader.java:362)
>
>
>
> Prueba el correo Terra ( http://www.terra.es/correo ); Seguro, rápido, fiable.
>
>

Hello,

It is perfectly normal for rxtx to return zero bytes depending upon how 
the timeout and threshold are set.  If you do not want the read to 
timeout, set it to zero.


*timeout threshold       Behavior
*------------------------------------------------------------------------
*0       0       blocks until 1 byte is available timeout > 0,
*                threshold = 0, blocks until timeout occurs, returns -1
*                on timeout
*>0      >0      blocks until timeout, returns - 1 on timeout, magnitude
*                of threshold doesn't play a role.
*0       >0      Blocks until 1 byte, magnitude of  threshold doesn't
*                play a role

I do not think defaults are documented so do not assume that they are the 
same between rxtx and sun.

--
Trent Jarvi
tjarvi at qbang.org