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Index › Programming Questions & Help › Syntax Questions › exit()/stop() confusion...
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exit()/stop() confusion... (Read 515 times)
alk509
exit()/stop() confusion...
Mar 18th, 2008, 8:31am  
Hello,

I've been playing around with Processing for a couple of hours now, and managed to put together a little RGB LED mixing program (three ControlP5 sliders controlling a three-color RGB LED hooked up to an Arduino). The program worked as expected, except that the LED was left on when the Processing window was closed. So I overloaded the stop() method to write a string of zeros to the serial port when the window closes...

This approach works just fine when running the sketch within the Processing environment, but if I export the application, the overloaded stop() method is no longer being called. I know I must be missing something stupid, but I can't figure it out! Here's my stop() code:


void stop() {
 outputString[0] = 0; // R
 outputString[1] = 0; // G
 outputString[2] = 0; // B
 
 port.write(outputString);
}


I searched the boards and saw some talk of calling super.stop() at the end of the above code, but that didn't help... Any other ideas?

Thanks!
Al.
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JohnG
Re: exit()/stop() confusion...
Reply #1 - Mar 18th, 2008, 10:20am  
Try changing it to
Code:
public void stop()
{
  outputString[0] = 0; // R
  outputString[1] = 0; // G
  outputString[2] = 0; // B
   
  port.write(outputString); 
  super.stop();
}


Note the "public"
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alk509
Re: exit()/stop() confusion...
Reply #2 - Mar 18th, 2008, 3:46pm  
Hi John,

Thanks for your reply. I tried your suggestion, but no luck... :-\

Any other ideas?

Best,
Al.
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adamh
Re: exit()/stop() confusion...
Reply #3 - Aug 2nd, 2009, 6:12pm  
alk509 - did you ever resolve this ?

I am having same issue, stop is not called when using export as application.

OSX 10.5.7
Processing 1.0.5
public stop declaration &  super.stop() as last command in method.
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PhiLho 
Re: exit()/stop() confusion...
Reply #4 - Aug 3rd, 2009, 3:02am  
From the PApplet core reference:
Quote:
public void stop()

   Called by the browser or applet viewer to inform this applet that it should stop its execution.

   Unfortunately, there are no guarantees from the Java spec when or if stop() will be called (i.e. on browser quit, or when moving between web pages), and it's not always called.

   Overrides:
       stop in class java.applet.Applet

In other words, it is called automatically by Java when running an applet.
I see in the source that it is also called by destroy() (also invoked automatically) and in the main loop when the animation thread is stopped. And some other places.

All this is useless if the system doesn't give the Java program a chance to stop gracefully.
Maybe you can look at Revelations on Java signal handling and termination article and see if you can handle the termination signal...
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