Re: synchronized, notify, wait,sleep, how to work together

From:
dsjoblom@abo.fi
Newsgroups:
comp.lang.java.programmer
Date:
7 Aug 2006 07:31:42 -0700
Message-ID:
<1154961102.434464.185880@h48g2000cwc.googlegroups.com>
John_Woo wrote:

Hi,

let's look at the following:

    class GetConnection extends Thread
    {
           Connection con = null;
               boolean done = false;

        public void run()
        {
            try{
                con = DriverManager.getConnection(...);
                //notifyAll();
                                done = true;
            }
            catch(Exception e){}
        }

        synchronized Connection getConnection()
        {
            return con;
        }
        synchronized boolean getDone()
        {
            return done;
        }
    }

questions:
supposed in some cases it may take up to 10-20 seconds to get the
connection while other cases just takes 1-3 seconds.
what can I code in caller method, so that
1. if in 5 seconds, interrupte GetConnection thread if it has not yet
finished;
2. preventing "done" being written while trying to interrupt this
thread.


This is a classical producer-consumer problem. Read
http://java.sun.com/docs/books/tutorial/essential/concurrency/index.html
to get familiar with the basics.

If you are using java 1.5 or later, it's easiest to implement this
using a BlockingQueue. See
http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/BlockingQueue.=
html

The producer thread that creates the Connection puts the connection
into the queue using the offer method, and the consumer thread that
desires to use the connection uses the poll method with desired
timeout. If the consumer doesn't get an object (poll returns null), it
can interrupt the producer thread.

You may wish to try to implement this from scratch though, to
familiarize yourself with the concepts. See the first link I posted for
more information.

Regards,
Daniel Sj=F6blom

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