Scala nested for loop - scala

Question

I'm a new Scala fellow and using processing library in scala ,I have 2 questions here:
val grid: Array[Cell] = Array()
val w = 60
val rows = height/w
val cols = width /w
override def setup(): Unit = {
for(j <- 0 until rows;
i <- 0 until cols){
val cell = new Cell(i,j)
grid :+ cell
println(s"at row : $j, at col: $i") //it compiles only once (at row : 0,
} //at col: 0 )
}
override def draw(): Unit = {
background(0)
grid.foreach(cell => cell.display())//nothing happens
}
but if i replace the variables rows & cols by height/w & width/w in the nested loop as follows:
for(j <- 0 until height/w;
i <- 0 until width/w){
val cell = new Cell(i,j)
grid :+ cell
println(s"at row : $j, at col: $i") //it compiles ordinary as nested
} //for loop
the second question is in the class Cell here:
class Cell(i: Int,j:Int){
def display(): Unit = {
val x = this.i * w
val y = this.j * w
println("it works")//doesn't work
//creating a square
stroke(255)
line(x,y,x+w,y)//top
line(x+w,y,x+x,y+w)//right
line(x,y+w,x+w,y+w)//bottom
line(x,y,x,y+w)//left
}
}
the method display doesn't work when calling at function draw() but no errors show up

Answer 1

Use tabulate to initialise your Array:
val grid = Array.tabulate(rows * cols) { i => new Cell(i % cols, i / cols) }
If you still have a problem with the display function then please post it as a separate question.