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

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.