How to append objects to an array

cadavara

I don't know which type grid has to be, it's confusing.

Cell cell;
int cols, rows;
int size = 40;
Cell[] grid;

void setup(){
  size(800, 600);
  background(255);
  cols = floor(width/size);
  rows = floor(height/size);

  for(int i = 0; i < rows; i++){
    for(int j = 0; i < cols; j++){
      cell = new Cell(i, j);
      grid.append(cell);
    }
  }
}

void draw(){
  background(255);
}

class Cell{
  int i, j;

  Cell(int _i, int _j){
    i = _i;
    j = _j;
  }
}

GoToLoop

Java arrays only got methods from the universal class Object, plus the field length and nothing more:
http://docs.Oracle.com/javase/8/docs/api/java/lang/Object.html

Processing's append() function is for occasionally grow the array. Shouldn't be abused due to performance & practical reasons.

Read more about it at these old forum links below:

1. https://forum.Processing.org/two/discussion/17524/why-can-t-i-append-a-new-vector-to-an-array-of-vectors#Item_8
2. https://forum.Processing.org/two/discussion/16923/appending-x-y-values-to-an-indexed-array#Item_5

cadavara

Well, I did some changing and now I get a NullPointerException at line 14. i fixed it

Cell[] cells;
int cols, row;
int s = 40;

void setup() {
  size(800, 600);
  background(255);
  cols = floor(width/s);
  row = floor(height/s);
  int cellsize = cols*row;
  cells = new Cell[cellsize];

  int index = 0;
  for (int i = 0; i < row; i++) {
    for (int j = 0; j < cols; j++) {
      cells[index] = new Cell(i, j, s);
      index += 1;
    }
  }
}

void draw() {
  background(255);

  for (int i = 0; i < cells.length; i++) {
    cells[i].show();
  }
}

class Cell {
  int i, j;
  int x, y;
  int s;

  Cell(int _i, int _j, int _s) {
    i = _i;
    j = _j;
    s = _s;
  }

  void show() {
    x = i*s;
    y = j*s;
    stroke(0);
    noFill();
    rect(x, y, s, s);
  }
}