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Re: how to read back the lines printed out to the console?

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On 01/30/2012 06:49 PM, frame wrote:
> Thank you very much for all the replies. Probably I didn't explain my
> question clear. After reading all the replies, I am sorry I still
> didn't get the idea to proceed.
>
> My problem is such: our finished Java program has many printing
> statements, e.g.
>
> System.out.println("step A: everything is ok");
> ...
> System.out.println("step B: computation starts now");
> ...
>
> if(so)
> {
> System.out.println("warning: temperature is too hot");
> }
>
> There are about 500 of those. When we run the program, all these
> messages show up on the console -- that's good. But now, we also want
> to keep those messages in a file.  I have two ideas, but none of them
> is acceptable:
>
> 1)at the beginning of the program, I added a little piece of code(re-
> direct the System output to a file), now all the existing 500
> System.out.println(..) prints to a file, not the console any more --
> this is not good, because the program runs up to 5 hours, we hope to
> see the message progressively on the console. With this approach, we
> have to wait till the program finished and open the text file to read.
> 2)another approach, use log4j to replace those 500 printing statements
> -- we are not ready for this approach right now, because there are 500
> of them -- in many classes. log4j has different levels(INFO, WARNING,
> ERROR etc). We need to analyze every printing case to decide its
> level. It is a too big approach for now.
>
> Ideally, I was wondering if this is possible: at the end of the
> program, when all those messages have been printed out to the console,
> I can added a small piece of code, which will read all the lines on
> the console back, then write them into a text file. I don't know if
> this makes sense.

People have already answered this question in detail, with code examples.

But what you really need to do is take the suggestion to use a logging 
framework. Then you can change the configuration in a properties file with no 
code changes.  500 instances isn't very many, especially with a global 
's/System.out.println/logger.info/'. Any decent IDE will let you do that in a 
single pop.

Do that. Really. It's the right thing to do.

-- 
Lew
Honi soit qui mal y pense.
http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg

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how to read back the lines printed out to the console? frame <xsli2@yahoo.com> - 2012-01-30 12:03 -0800
  Re: how to read back the lines printed out to the console? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-01-30 20:18 +0000
    Re: how to read back the lines printed out to the console? Roedy Green <see_website@mindprod.com.invalid> - 2012-01-30 20:42 -0800
  Re: how to read back the lines printed out to the console? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-01-30 14:18 -0800
    Re: how to read back the lines printed out to the console? Arne Vajhøj <arne@vajhoej.dk> - 2012-01-30 19:34 -0500
  Re: how to read back the lines printed out to the console? Patricia Shanahan <pats@acm.org> - 2012-01-30 14:37 -0800
    Re: how to read back the lines printed out to the console? Arne Vajhøj <arne@vajhoej.dk> - 2012-01-30 20:08 -0500
      Re: how to read back the lines printed out to the console? Patricia Shanahan <pats@acm.org> - 2012-01-30 17:18 -0800
        Re: how to read back the lines printed out to the console? Arne Vajhøj <arne@vajhoej.dk> - 2012-01-30 21:00 -0500
  Re: how to read back the lines printed out to the console? Arne Vajhøj <arne@vajhoej.dk> - 2012-01-30 19:33 -0500
    Re: how to read back the lines printed out to the console? Arne Vajhøj <arne@vajhoej.dk> - 2012-01-30 19:35 -0500
    Re: how to read back the lines printed out to the console? frame <xsli2@yahoo.com> - 2012-01-31 10:09 -0800
      Re: how to read back the lines printed out to the console? Lew <noone@lewscanon.com> - 2012-01-31 11:11 -0800
        Re: how to read back the lines printed out to the console? Arne Vajhøj <arne@vajhoej.dk> - 2012-01-31 20:39 -0500
        Re: how to read back the lines printed out to the console? frame <xsli2@yahoo.com> - 2012-02-01 06:01 -0800
          Re: how to read back the lines printed out to the console? Ian Shef <invalid@avoiding.spam> - 2012-02-01 19:15 +0000
            Re: how to read back the lines printed out to the console? frame <xsli2@yahoo.com> - 2012-02-01 12:59 -0800
              Re: how to read back the lines printed out to the console? Gene Wirchenko <genew@ocis.net> - 2012-02-01 14:00 -0800
          Re: how to read back the lines printed out to the console? Arne Vajhøj <arne@vajhoej.dk> - 2012-02-01 19:27 -0500
  Re: how to read back the lines printed out to the console? frame <xsli2@yahoo.com> - 2012-01-30 18:49 -0800
    Re: how to read back the lines printed out to the console? Arne Vajhøj <arne@vajhoej.dk> - 2012-01-30 21:56 -0500
    Re: how to read back the lines printed out to the console? Patricia Shanahan <pats@acm.org> - 2012-01-30 19:06 -0800
    Re: how to read back the lines printed out to the console? Roedy Green <see_website@mindprod.com.invalid> - 2012-01-30 20:46 -0800
    Re: how to read back the lines printed out to the console? Lew <noone@lewscanon.com> - 2012-01-30 21:18 -0800
      Re: how to read back the lines printed out to the console? Arne Vajhøj <arne@vajhoej.dk> - 2012-01-31 20:36 -0500
    Re: how to read back the lines printed out to the console? Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2012-01-31 10:18 +0200
      Re: how to read back the lines printed out to the console? Lew <noone@lewscanon.com> - 2012-01-31 11:15 -0800
    Re: how to read back the lines printed out to the console? bugbear <bugbear@trim_papermule.co.uk_trim> - 2012-01-31 09:50 +0000
      Re: how to read back the lines printed out to the console? Lew <noone@lewscanon.com> - 2012-01-31 11:17 -0800

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