How to add PVectors into 2D Arraylist?

szemy2

Hey guys,

I would like to dynamically add new triangles (defined by its vertexes being PVectors). I don't know how many triangles I will have, so I would like to use a 2D Arraylist.

How do I add elements to this double array? My code doesn't work because array.get(i) (obviously) returns null. How do I add a new PVector to i,j?

Here is my code so far:

ArrayList<ArrayList<PVector>> array = new ArrayList<ArrayList<PVector>>();

void setup()
{
  for (int i=0; i<1; i++) {           
    for (int j=0; j<3; j++) {   
      array.get(i).get(j).add(new PVector(0, 0, 0));
    }
  }

  for (int i=0; i<array.size(); i++) {         
    for (int j=0; j<array.get(i).size(); j++) {  
      println(array.get(i).get(j).x);
    }
  }
}

Thanks for any reply:)

(I have found this discussion but I'm missing the iterration: https://forum.processing.org/one/topic/2d-arraylist.html)

Chrisir

When yoi have a ClassTriangle your ArrayList could be of that type

Much easier (in the longrun)

szemy2

Thank you for that answer, Ill try to do it that way:)

However, if anyone is interested in a more generic solution, I made it work:

ArrayList<ArrayList<PVector>> array = new ArrayList<ArrayList<PVector>>();

void setup()
{
  for (int i=0; i<2; i++) { 
    array.add(new ArrayList<PVector>());
   for (int j=0; j<3; j++) {   
     array.get(i).add(new PVector(i, 0, j));  //.get(j).add(new PVector(0, 0, 0));
   }
  }

  for (int i=0; i<array.size(); i++) {         
    for (int j=0; j<array.get(i).size(); j++) {  
      println(array.get(i).get(j));
    }
  }
}

GoToLoop

@szemy2, you can replace the internal ArrayList<PVector> w/ just PVector[]: *-:)

// forum.Processing.org/two/discussion/16383/
// how-to-add-pvectors-into-2d-arraylist

// GoToLoop (2016-May-02)

import java.util.List;

static final int VERTS = 3;
final List<PVector[]> trigs = new ArrayList<PVector[]>();

void setup() {
  for (int i = 0; i < 2; ++i) {
    trigs.add(new PVector[VERTS]);

    for (int j = 0; j < VERTS; ++j)
      trigs.get(i)[j] = PVector.random2D(this);
  }

  for (final PVector[] t : trigs)  println(t);
  exit();
}