[Threading to manage simulated printing jobs]

Hello to all Javascript programmers out there. :)

I am really ashamed to say that even after 6 months of intermittent
Java programming I have been a complete failure at grasping the
concepts or the real thing behind 'threading'. My mind just seems to
go in a state of deadlock and I keep hours looking at the screen
trying to come up with a design to get the problem solved using
threads. I am OK with normal Java programs. Also here in my case I
have not used the convenience classes provided by java so that I can
get my concepts right.

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.

import java.sql.Timestamp;
import java.util.*;

public class ThreadTime {
    @SuppressWarnings("unused")
    public static void main(String[] args) throws Exception {
        PrintQueue queue = new PrintQueue();
        Producer producer = null;
        for (int i = 0; i < 100; ++i) {
            producer = new Producer(queue, "c:/" + i + ".txt");
        }
        new Consumer(queue);
        new Consumer(queue);
        new Consumer(queue);
    }
}

class Consumer {
    private static int gId;

    private PrintQueue queue;

    private String id;

    private 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();
            }
        }
    };

    public Consumer(PrintQueue queue) throws Exception {
        this.queue = queue;
        this.id = "Consumer" + gId;
        gId++;
        Thread t = new Thread(job);
        t.join(); /* Does this even do anything? */
        t.start();
    }
}

class Producer {
    private PrintQueue queue;

    private String file;

    public Producer(PrintQueue queue, String file) throws Exception {
        this.queue = queue;
        this.file = file;
        Thread t = new Thread(job);
        t.join(); /* Does this even do anything? */
        t.start();
    }

    private Runnable job = new Runnable() {
        public void run() {
            try {
                //System.out.println("Inside run of producer");
                Thread.sleep(500);
                queue.putJob(new PrintJob(file, new Timestamp(new Date()
                        .getTime())));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    };
}

class PrintQueue {
    public List<PrintJob> queue;

    public static int jobId;

    public PrintQueue() {
        queue = new LinkedList<PrintJob>();
    }

    public synchronized PrintJob getJob() {
        if (queue.size() != 0)
            return (queue.remove(0));
        else
            return (null);
    }

    public synchronized void putJob(PrintJob job) {
        queue.add(job);
    }
}

class PrintJob {
    private static int jobId;

    public int id;

    public Timestamp time;

    public String path;

    public PrintJob(String path, Timestamp time) {
        this.id = jobId;
        this.path = path;
        this.time = time;
        jobId++;
    }

    private PrintJob() {
    }

    public String print() {
        return (this.toString());
    }

    public String toString() {
        return (" Id: " + id + " Path: " + path + " Time: " + time);
    }
}

Thanks a lot for your valuable time.

Regards,
S T S