Re: TimerTask as Filewatcher.

From:

Knute Johnson <nospam@rabbitbrush.frazmtn.com>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 31 Oct 2007 21:47:26 -0700

Message-ID:

<BTcWi.129$mN1.0@newsfe17.lga>

smartnhandsome wrote:

Thanks every one for there replies, but the code still works like the
same way as I had written, when we create a TimerTask and override the
run method and pass this to timer it creates a new thread and then
pass back the control to the main thread, so the main thread still
keeps doing next steps while the timer thread that was created earlier
would run back ground. I wanted my code (main thread ) to wait till
timer task thread finishes its file watch. How can this be achieved??

Thanks again for every ones posts.

do {
     File f = new File("????");
     if (f.exists())
         break;
     try {
         Thread.sleep(1000);
     } catch (InterruptedException ie) { }
} while (true) ;

But if the file never shows up your program never runs again. I would
use this instead of a TimerTask, it is inline and simpler if you want to
halt your program until the file arrives.

If you insist on a TimerTask;

use a boolean flag and a wait object

boolean flag;
final Object o = new Object();

// main thread
synchronized (o) {
     while (!flag)
         o.wait();
     flag = false;
}

// TimerTask...
if (f.exists())
     synchronized (o) {
         flag = true;
         o.notify();
     }

--

Knute Johnson
email s/nospam/knute/