Beginners question: WHAT DOES THIS MEAN?

Integration and Hardware

w_course

Beginners question: WHAT DOES THIS MEAN?

in Integration and Hardware • 5 months ago

Exception in thread "Animation Thread" java.lang.NullPointerException

at Breathing_proccessing_visuals.draw(Breathing_proccessing_visuals.java:37)

at processing.core.PApplet.handleDraw(PApplet.java:2266)

at processing.core.PGraphicsJava2D.requestDraw(PGraphicsJava2D.java:243)

at processing.core.PApplet.run(PApplet.java:2140)

at java.lang.Thread.run(Thread.java:680)

I've been trying to draw using processing and an arduino with sensor. The code is fairly basic but I'm fairly sure it's good to do what I want however each time I go play it on processing I get this message. Is this a problem with the code or with the drivers etc. on my computer?

Full code for context:

import processing.serial.*;

import cc.arduino.*;

Arduino W;

void setup() {

background(51);

size(800,600);

}

void draw(){

int pot1 = W.analogRead(0);

ellipse(100,100,100,100);

fill(pot1,pot1/12);

}

Replies(5)

Chrisir

Re: Beginners question: WHAT DOES THIS MEAN?

5 months ago

this

background(51);
size(800,600);

should be

size(800,600);
background(51);

w_course

Re: Beginners question: WHAT DOES THIS MEAN?

5 months ago

Thanks for taking the time. Unfortunately this didn't seem to cure the problem.

If it is something to do with the code would it be the 'int' line as this is highlighted with the 'problem text?' If so does it need defining in the setup?

velvetkev..

Re: Beginners question: WHAT DOES THIS MEAN?

5 months ago

Yes, it looks like you've declared but not initialised your Arduino object (W).

You'll need something like

               
                 W = new Arduino(this, Arduino.list()[0], 57600);
               
inside setup().

Some docs here with sample code.

You didn't specify which version of Processing you're using but be aware that the Firmata library currently

only works with 1.5.1 as far as I know.

HTH.

w_course

Re: Re: Beginners question: WHAT DOES THIS MEAN?

5 months ago

Thankyou seems to have done the trick :)

PhiLho

Re: Beginners question: WHAT DOES THIS MEAN?

5 months ago

Hint about your subject line: try to be more descriptive.
We don't really care that you are a beginner, about half of the people asking questions here are beginners...
Avoid using all caps, it looks like you yell.
And we have no idea of what "THIS" is...
Something like: "What is a NullPointerException" would have been better...

Note: you can be interested by the articles in the Technical FAQ, there is one about your problem.