Listening changes on a text file (Unix Tail implementation with Java)

11 Comments Published November 19th, 2005 in Java Tags: .

public class Tail {
    public static void main(String[] args) throws IOException {
        Reader fileReader = new FileReader(args[0]);
        BufferedReader input = new BufferedReader(fileReader);
        String line = null;
        while (true) {
            if ((line = input.readLine()) != null) {
                System.out.println(line);
                continue;
            }
            try {
                Thread.sleep(1000L);
            } catch (InterruptedException x) {
                Thread.currentThread().interrupt();
                break;
            }
        }
        input.close();
    }
}

Easy enough to be posted without any comment :-)

11 Responses to “Listening changes on a text file (Unix Tail implementation with Java)”

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1 Roger Nov 1st, 2006 at 23:33

God, Have been looking everywhere for that!!!

Geeze, everyone else’s is like 100000 lines of code, i can’t believe it was that simple.

THANK YOUUUUUUU !!!!!!!
2 Gozala Jan 10th, 2008 at 12:05

Thank you!!
exactly what I was looking for!!
3 borras Jul 10th, 2008 at 11:22

great !!!
4 hans Sep 4th, 2008 at 18:38

great job.
5 Waste Mar 13th, 2009 at 09:37

Not of any use.
It just lists the contents of the given file once and keeps on running in a loop and does not shows the new lines added to the given file.
6 antonio Mar 13th, 2009 at 10:47

hehehe. are you out of your mind?
7 Alessandro Melandri May 2nd, 2009 at 10:16

Great job! This saves me a lot of time! I’ve done some little customization to this class: http://www.melandri.net/java/tail
8 James Mar 16th, 2010 at 22:56

Thank you!!!!!!!
9 Sanka Apr 12th, 2010 at 17:37

It just simple does not work with log files rotated with log4j…I mean this code does prevent log4j from rotating !
10 Chamara Silva Apr 25th, 2011 at 10:51

Great post. thank you.

/Chamara Silva