🚀 go-pugleaf

George wrote:

> I want to capture the standard output of a console program written in C in a
> JTextArea component.  The code I am running is shown below.  The issue I
> have is:  it takes inordinately long for the the first line of    output to
> appear; and when it does all of the ouput (about 20 lines) appears together.
> This is not the case if I run the program from the DOS prompt.  Any ideas
> why the behavior is different when the program is run under control of a
> Java program?
> 
>      cycleProcess = rt.exec(command, null, currentDir);
>         InputStreamReader isr = new
> InputStreamReader(cycleProcess.getInputStream());
>         batchLogReader = new LineNumberReader(isr);
>         outputLine = batchLogReader.readLine();
>         while (outputLine  != null) {
>           outputLine = batchLogReader.readLine();
>           messagesTextArea.setText(messagesTextArea.getText() + "\n" +
> outputLine);
>           messagesTextArea.paintImmediately(messagesTextArea.getBounds());
>         }
> 
> 

Generally streams don't flush to output until their buffers are full. 
If you want to see intermediate results, you should use flush().

-- 

Regards,

Lori Olson [TeamB]

------------

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Lori M Olson [TeamB] wrote:

> George wrote:
> 
>> I want to capture the standard output of a console program written in 
>> C in a
>> JTextArea component.  The code I am running is shown below.  The issue I
>> have is:  it takes inordinately long for the the first line of    
>> output to
>> appear; and when it does all of the ouput (about 20 lines) appears 
>> together.
>> This is not the case if I run the program from the DOS prompt.  Any ideas
>> why the behavior is different when the program is run under control of a
>> Java program?
>>
>>      cycleProcess = rt.exec(command, null, currentDir);
>>         InputStreamReader isr = new
>> InputStreamReader(cycleProcess.getInputStream());
>>         batchLogReader = new LineNumberReader(isr);
>>         outputLine = batchLogReader.readLine();
>>         while (outputLine  != null) {
>>           outputLine = batchLogReader.readLine();
>>           messagesTextArea.setText(messagesTextArea.getText() + "\n" +
>> outputLine);
>>           
>> messagesTextArea.paintImmediately(messagesTextArea.getBounds());
>>         }
>>
>>
> 
> Generally streams don't flush to output until their buffers are full. If 
> you want to see intermediate results, you should use flush().
> 

Oops.  That's not an output stream.  Sorry.

You are doing screen update work in your main thread, which is not going 
to work.  You should investigate the usage of SwingUtilities.invokeLater.

http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html

-- 

Regards,

Lori Olson [TeamB]

Actually the timing issue seems to be in getting back the first line from
the BufferedReader.  I put in some print statement into the code which is
shown below:  I also show the timings printed out in the JBuilder output
window

        cycleProcess = rt.exec(command, null, currentDir);
        System.out.println("Starting to read output " + new Date());
        InputStreamReader isr = new
InputStreamReader(cycleProcess.getInputStream());
        batchLogReader = new LineNumberReader(isr);
        System.out.println("Streams created " + new Date());
        outputLine = batchLogReader.readLine();
        System.out.println("First line received " + new Date());
        while (outputLine  != null) {
//          messagesTextArea.setText(messagesTextArea.getText() + "\n" +
outputLine);
//          messagesTextArea.paintImmediately(messagesTextArea.getBounds());
          SwingUtilities.invokeAndWait(new OutputHandler());
          outputLine = batchLogReader.readLine();
        }
        System.out.println("All lines received " + new Date());

Here is the sequence of print statements as output in a trial run

Starting to read output Tue Jun 22 10:08:38 EDT 2004
Streams created Tue Jun 22 10:08:38 EDT 2004
First line received Tue Jun 22 10:09:05 EDT 2004
All lines received Tue Jun 22 10:09:06 EDT 2004

As you can see most of the time is spent in waiting for the first line to
arrive.....



"Lori M Olson [TeamB]" <javadragon@techie.com> wrote in message
news:40d74a22$1@newsgroups.borland.com...
> Lori M Olson [TeamB] wrote:
>
> > George wrote:
> >
> >> I want to capture the standard output of a console program written in
> >> C in a
> >> JTextArea component.  The code I am running is shown below.  The issue
I
> >> have is:  it takes inordinately long for the the first line of
> >> output to
> >> appear; and when it does all of the ouput (about 20 lines) appears
> >> together.
> >> This is not the case if I run the program from the DOS prompt.  Any
ideas
> >> why the behavior is different when the program is run under control of
a
> >> Java program?
> >>
> >>      cycleProcess = rt.exec(command, null, currentDir);
> >>         InputStreamReader isr = new
> >> InputStreamReader(cycleProcess.getInputStream());
> >>         batchLogReader = new LineNumberReader(isr);
> >>         outputLine = batchLogReader.readLine();
> >>         while (outputLine  != null) {
> >>           outputLine = batchLogReader.readLine();
> >>           messagesTextArea.setText(messagesTextArea.getText() + "\n" +
> >> outputLine);
> >>
> >> messagesTextArea.paintImmediately(messagesTextArea.getBounds());
> >>         }
> >>
> >>
> >
> > Generally streams don't flush to output until their buffers are full. If
> > you want to see intermediate results, you should use flush().
> >
>
> Oops.  That's not an output stream.  Sorry.
>
> You are doing screen update work in your main thread, which is not going
> to work.  You should investigate the usage of SwingUtilities.invokeLater.
>
> http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html
>
> -- 
>
> Regards,
>
> Lori Olson [TeamB]
>