I'm trying to write some code to start out with using the Arduino with Processing. I decided to start out by alering the beginners' exaple of integrating a mouse to move a line with a small thumb pad.
The vertical and horizontal potentiometers are attached to analog pins 1 and 0.

I've worked through a number of bugs on my own, but I don't quite know what the problem is here.


Code:

import processing.serial.*;
import cc.arduino.*;

Arduino arduino;
int verPin = 0;
int horPin = 1;
float ver = 1;
float hor = 2;

void setup() {
  size(400, 400);
  stroke(255);
  arduino.pinMode(verPin, Arduino.INPUT);
  arduino.pinMode(horPin, Arduino.INPUT);
}

void draw() {
  background(192, 64, 0);
  ver = arduino.analogRead(verPin);
  ver = map(ver, 0, 1023, 0, height);
  hor = arduino.analogRead(horPin);
  hor = map(hor, 0, 1023, 0, width);
  line(width/2, height/2, hor, ver);
}
 

I keep getting the error:


NullPointerException

Exception in thread "Animation Thread" java.lang.NullPointerException
     at sketch_may25b.setup(sketch_may25b.java:32)
     at processing.core.PApplet.handleDraw(PApplet.java:1400)
     at processing.core.PApplet.run(PApplet.java:1328)
     at java.lang.Thread.run(Unknown Source)




Whats up? What am I doing wrong?

So that stopped the errors, but when I run the following code I get nothing.

Code:

import processing.serial.*;
import cc.arduino.*;

Arduino arduino;
int verPin = 0;
int horPin = 1;
float ver = 1;
float hor = 2;

void setup() {
  size(400, 400);
  stroke(255);
  arduino = new Arduino(this, Arduino.list()[0], 9600);
  arduino.pinMode(verPin, Arduino.INPUT);
  arduino.pinMode(horPin, Arduino.INPUT);
}

void draw() {
  background(192, 64, 0);
  ver = arduino.analogRead(verPin);
  ver = map(ver, 0, 1023, 0, height);
  hor = arduino.analogRead(horPin);
  hor = map(hor, 0, 1023, 0, width);
  line(width/2, height/2, hor, ver);
}
 

I have the following code running on my Arduino, and the serial monitor on the Arduino's GUI is spitting out proper numbers.

Code:

int verPin = 0;
int horPin = 1;
int ver = 234;
int hor = 456;

void setup()
{
  Serial.begin(9600);
  pinMode(verPin, INPUT);
  pinMode(horPin, INPUT);
}

void loop()
{
  ver = analogRead(verPin);
  ver = map(ver, 0, 1023, 0, 100);
  hor = analogRead(horPin);
  hor = map(hor, 0, 1023, 0, 100);
  Serial.print("Vertical   ");
  Serial.println(ver);
  Serial.print("Horizontal ");
  Serial.println(hor);
  delay(100);
}
 

Nothing happens to the line in the Processing window, what's wrong now that there's not an error message?

The Tx and Rx indicators on my Arduino do nothing when I run the sketch. Where do I find out or set which port Processing reads the Arduino from?

In Arduino I've it hooked up to COM4.

In Processing, when I run the following of code:
Code:

import processing.serial.*;
import cc.arduino.*;

Arduino arduino;
int verPin = 0;
int horPin = 1;
float ver = 1;
float hor = 2;

void setup() {
  size(400, 400);
  stroke(255);
  println(Arduino.list());
  arduino = new Arduino(this, Arduino.list()[0], 9600);
  arduino.pinMode(verPin, Arduino.INPUT);
  arduino.pinMode(horPin, Arduino.INPUT);
}

void draw() {
  background(192, 64, 0);
  ver = arduino.analogRead(verPin);
  ver = map(ver, 0, 1023, 0, height);
  hor = arduino.analogRead(horPin);
  hor = map(hor, 0, 1023, 0, width);
  line(width/2, height/2, hor, ver);
}
 

I no longer get an error message, and it tells me that there's an Arduino connected to COM4, but the Processing sketch still wont do anything.

When I run it, the Tx/Rx lights don't flash.

Alright so I uploaded the Firmata, apparently that was one of my problems as well.

Unfortunately... it still doesn't work.
Is there a place in the program where I have to specify which COM port the arduino is attached to? Processing picks it up, because at teh bottom it shows the following, but the program still doesn't respond to the hardware.

Stable Library
=========================================
Native lib Version = RXTX-2.1-7
Java lib Version   = RXTX-2.1-7
[0] "COM3"
[1] "COM4"

HAHAHAHAHA IT WORKS!

Thanks man, all I needed were the quotation marks around COM4. I am eternally grateful, as you've just helped me over a huge hurdle for me (and my college major).