UNIX Pipe(tail command) and java

Question

I want to read from a LOG file, which is being appended periodically. I have written a java program which can process on the addition made to the LOG file and display the result (as soon as something is added to the LOG file)
My prgram works fine if I use:
tail -500 input.LOG | java myprogbut when I use:
tail -f input.LOG | java myprognothing is displayed on the screen.
Wat could be the solution? So that myprogram keeps on processing the updated file and displays the result on the screen as soon as LOG file is appended with new data?
Here is my JAVA code: It reads a line and store it into an ArrayList.
ArrayList alBuffer = new ArrayList();
try{
InputStreamReader reader = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(reader);
String strLine;
int count = 0;
while((strLine=br.readLine())!=null){
System.out.println("<NEWLINE("+count+")>:"+strLine);
alBuffer.add(count,strLine);
++count;
}catch(Exception exc){
System.out.println("EXCEPTION WHILE READING");
exc.printStackTrace();
}Thanks,
Sumit

Answer 1

Needed something similar and I came up with this, not much of a change from your existing code.
BufferedReader IN = new BufferedReader(new FileReader("log.txt"));
EXECUTE = true;
String line;
while(EXECUTE){
          line = IN.readLine();
          if(line != null){
                    //do something with the text......
          else{
                 try{
                        Thread.sleep(500);
                 } catch(Throwable t){}
}For a tail you do not want the EOF or a null to stop the reader, instead, if you read a null or EOF from the buffered reader you just ignore it, sleep for a while and try again. This saves you having to read through the file again or use the mark method!!
Hope this helps......
/P/