();
}
function addParticle() {
particles.add(new Particle(origin));
}
function run() {
for (float i = particles.size()-1; i >= 0; i--) {
Particle p = particles.get(i);
p.run();
// if (p.isDead()) {
// particles.remove(i);
// }
}
}
function move_away_from( var x, var y){
for(Particle p : particles){
var d = dist(x,y,p.position.x, p.position.y);
if( d < 200 ){
p.velocity.x += map(d,0,200,0.5,0.1)*(p.position.x - x);
p.velocity.y += map(d,0,200,0.5,0.1)*(p.position.y - y);
}
}
}
}
class Particle {
PVector position;
PVector velocity;
PVector acceleration;
PVector home;
Particle(PVector l) {
acceleration = new PVector(0, 0);
velocity = new PVector(0,0);//random(-0.0001, 0.00001), random(-0.001, 0.0001));
l=new PVector(random(0, 1200), random(0, 800));
position = l.copy();
home = position.copy();
}
function run() {
update();
display();
}
// Method to update position
function update() {
acceleration.x = -0.01*(position.x - home.x);
acceleration.y = -0.01*(position.y - home.y);
velocity.add(acceleration);
velocity.mult(0.9);
position.add(velocity);
// lifespan -= 1.0;
}
// Method to display
function display() {
noStroke();//stroke(255, lifespan);
//fill(255, lifespan);
fill(0);
ellipse(position.x, position.y, 25, 25);
}
}
```
So if anyone has got the solution or can tell me the steps i need to take please let me know!
---
### Author:  [@kll](https://discourse.processing.org/u/kll)
#### Post date: [October 25, 2019, 2:46am UTC](https://discourse.processing.org/t/converting-my-processing-code-to-p5-js-arraylist-others/14936/2 "2019-10-25T02:46:54Z")
-a- where you have the JAVA code from?
if that is a tutorial it might be also available as p5.js already
so google first
-b- p5.js coding questions are best
if you setup it as MVCS on
[https://editor.p5js.org/](https://editor.p5js.org/)
so we see with one click code / error / result…
and can link back to you suggested repairs
-c- p5.js array: different, not arrayList:
[https://p5js.org/reference/#group-Data](https://p5js.org/reference/#group-Data)
-d- p5.js Vector:
[https://p5js.org/reference/#/p5.Vector](https://p5js.org/reference/#/p5.Vector)
---
### Author:  [@GoToLoop](https://discourse.processing.org/u/GoToLoop)
#### Post date: [October 26, 2019, 2:31am UTC](https://discourse.processing.org/t/converting-my-processing-code-to-p5-js-arraylist-others/14936/3 "2019-10-26T02:31:18Z")
> [@Rod1C](#):
>
> ```auto
> class ParticleSystem {
> ArrayList particles;
> PVector origin;
>
> ParticleSystem(PVector position) {
> origin = position.copy();
> particles = new ArrayList();
> }
>
> function addParticle() {
> particles.add(new Particle(origin));
> }
>
> // ...
> }
>
> ```
That’s not how we define classes’ constructor, methods & fields under JS syntax!
You should read the JS reference for it:
> **[Classes - JavaScript | MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes)**
>
> Classes are a template for creating objects. They encapsulate data with code to work on that data. Classes in JS are built on prototypes but also have some syntax and semantics that are unique to classes.
Also, there’s no ArrayList either. We use JS arrays instead:
> **[Indexed collections - JavaScript | MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Indexed_collections#Array_object)**
>
> This chapter introduces collections of data which are ordered by an index value. This includes arrays and array-like constructs such as Array objects and TypedArray objects.
And while in Java we can generally omit the keyword `this` before accessing a class member, in JS it’s mandatory:
[ ](https://www.youtube.com/watch?v=M5d7vygUPoQ)
Now w/ all the info above, here’s a partial but proper JS conversion of your `class` ParticleSystem:
```auto
class ParticleSystem {
constructor(position) {
this.origin = position.copy();
this.particles = [];
}
addParticle() {
this.particles.push(new Particle(this.origin));
}
// ...
}
```