Problem with ArrayList<Float>

Processing Beginners
1

I stumbled upon a problem a few times. It’s either this or error: index: 0 size: 0. Why is this happening. I am relatively new to this but I can’t do anything. It sometimes fixes on itself and at other times it just doesn’t.

ArrayList<Float> x = new ArrayList<Float>();
ArrayList<Float> y = new ArrayList<Float>();
ArrayList<Float> a = new ArrayList<Float>();

ArrayList<Float> px = new ArrayList<Float>();
ArrayList<Float> py = new ArrayList<Float>();
ArrayList<Float> pa = new ArrayList<Float>();

int n = 3, it = 0;
float l = 100, ba = -PI/2, spin = PI/3;
float spn[] = new float[3];

void setup() {
  size(600, 600);
  
  px.add(300);
  py.add(500);
  
  println(px.size());
  for(int i = 0; i < n; i++) {
    spn[i] = map(i,0,n-1,-spin/2,spin/2);
  }
  printArray(spn);
}

void draw() {
  background(0);
  stroke(255);
  for(int i = 0; i < px.size(); i++) {
    for(int j = 0; j < n; j++) {
      line(px.get(0) + l*cos(spn[j]+ba), py.get(0) + l*sin(spn[j]+ba), px.get(0),py.get(0));
    }
  }
  
}
2

error is here. It says
image

3

The arraylist expects a float and you are providing an integer, i can run your code by using 300.0 and 500.0 instead of 300 and 500. I guess arraylists do not work like methods and adhere to stricter variable types.

Alternatively you can cast it by using (float)300 and (float)500 or float(300) and float(500).

4

Alternatively he could just shift to a FloatList container instead, which is both less problematic & more performant: :racing_car:

Or even better, turn all those 6 containers into 1 class. :bulb:

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