Re: A question about Java Thread

From:

Marco <none@home.de>

Newsgroups:

comp.lang.java.programmer

Date:

Fri, 15 Jun 2007 10:11:39 +0200

Message-ID:

<f4thb8$uq0$1@aioe.org>

JTL.zheng wrote:

I see a code like this:

in a Thread:
--------------------------
public void run() {

  Thread currentThread = Thread.currentThread();

  while (thread == currentThread) {

    try {
      repaint();
      thread.sleep(100);
    }
    catch (InterruptedException ex) {
    }

  }
}
---------------------------

what's the "while (thread == currentThread) " codes mean?
what is it used for?

Usually one uses such constructs to determine the validity of the
thread. That means a Thread-Object holds a reference to itself ("thread"
in the example) which can be set to null from the _outside_ of the
thread. Any 100 ms the thread awakes and checks if it's "thread"
reference still points to itself or has been set to null. If it has been
set to null, the thread exits the while loop and therefore the run()
method returns (say: thread is dead).

whenever you see such constructs, you can be sure they are used to
signal the thread to exit.

But one more Point: Don't use the ref-name "thread" for a reference to a
"Thread" Object! This can easily be misunderstood.