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.