Re: [Threading to manage simulated printing jobs]

From:

Joshua Cranmer <Pidgeot18@verizon.net>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 09 Sep 2007 18:28:33 GMT

Message-ID:

<lXWEi.340$Z33.181@trndny08>

getsanjay.sharma@gmail.com wrote:

Here I have written a program which simulates a printing job in which
'Consumer' is a printing device or software and 'Producer' submits a
printing job. But the output I get is highly deterministic i.e. the
same everytime I don't even know if I have got it right or wrong. Some
comments / pointers / alternate designs / tips / revelations would be
greatly appreciated.

What is the output?

class Consumer {
    private Runnable job = new Runnable() {
        public void run() {
            // start consuming the print jobs and print them
            try {
                for (;;) {
                    //System.out.println("Inside run of producer");
                    Thread.sleep(10);
                    PrintJob job = queue.getJob();
                    if (job != null)
                        System.out.println(id + job.print());
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

> };

Two things:
1. Don't use tabs in Usenet posts.
2. There should typically be some way to tell the Consumer to stop running.

public Consumer(PrintQueue queue) throws Exception {

> [ ... ]

t.join(); /* Does this even do anything? */

Joining a thread waits for it stop. Since the thread hasn't started yet,
it doesn't do anything.

}
}

[ ... ]

Try posting some of the output so we could help better.

--
Beware of bugs in the above code; I have only proved it correct, not
tried it. -- Donald E. Knuth