Re: problems getting stderr and stdout from process object

From:

Lothar Kimmeringer <news200709@kimmeringer.de>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 24 Sep 2009 14:43:38 +0200

Message-ID:

<1jmhul6as3mc0.dlg@kimmeringer.de>

horos22 wrote:

BufferedReader br_err = new BufferedReader (new InputStreamReader
(stderr));
BufferedReader br_out = new BufferedReader (new InputStreamReader
(stdout));

while ((line = br_err.readLine ()) != null) { .. }
while ((line = br_out.readLine()) != null) { .. }

You have to put these two while-loops into two independent
threads. STDERR is open until the process ends, so br_err.readLine
will block until the process sends something on STDERR. If that
doesn't happen but something is given out on STDOUT, the buffer
there will be full sooner or later, blocking the process.

Another solution would be a polling-mechanism:

while (subProcessRunning()){
  if (br_err.availble() != 0){
    line = br_err.readLine();
    ...
  }
  if (br_out.availble() != 0){
    line = br_out.readLine();
    ...
  }
}

But I'm no friend of this kind of thing.

Regards, Lothar
--
Lothar Kimmeringer E-Mail: spamfang@kimmeringer.de
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