Re: a tight game loop in Swing

From:
Lew <noone@lewscanon.com>
Newsgroups:
comp.lang.java.gui
Date:
Thu, 07 Jun 2012 00:36:06 -0700
Message-ID:
<jqpll7$mee$1@news.albasani.net>
On 06/05/2012 09:51 PM, Knute Johnson wrote:

   public void run() {
         try {
             long now = 0;
             long then = System.nanoTime();

             while (true) {
                 render();
                 try {
                     EventQueue.invokeAndWait(new Runnable() {
                         public void run() {
                             paintImmediately(getBounds());
                         }
                     });
                 } catch (InvocationTargetException ite) {
                     System.out.println(ite);
                 }

                 /*
                 while (now < then + 10000000)
                     now = System.nanoTime();
                 then = now;
                 */
             }
         } catch (InterruptedException ie) {
             System.out.println(ie);
         }
     }


How about this formulation?

   @Override
   public void run() {
     for (boolean active = true; active; ) {
       try {
         render();
         try {
           EventQueue.invokeAndWait(new Runnable() {
               public void run() {
                 paintImmediately(getBounds());
               }
             });
         } catch (InvocationTargetException ite) {
           System.out.println(ite);
         }

         /*
         for (long pause = System.nanoTime() + 10000000L;
              System.nanoTime() < pause;
              ) {
         }
         */
       } catch (InterruptedException ie) {
         System.out.println(ie);
         active = false;
       }
     }
   }

I base this on vague, hence possibly superstitiously encoded memories of
Goetz's (et al.) _Java Concurrency in Practice_ and other sources.

He goes to some length to re-educate about 'InterruptedException'. I may have
got it wrong, but I seem to recall something about setting a loop condition
rather than leaping out pell-mell, and a tickle about a rethrow of the
interruption but that might be for specialized circumstances. Like when the
interruptee isn't the end of the line for handling that interrupt as it is here.

I read a book. I'm not an authority.

I loathe 'System.out' for logging. OTOH, in this case the point of the program
arguably is the exception output, so it's legit, right?

--
Lew
Honi soit qui mal y pense.
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