Array Index Out of Bound Exception - Scala - arrays

Question

I want to print a two dimensional matrix in Scala and I keep getting Array Index Out of Bound Exception.
I have used breakable code and still I am encountering the issue.
package com.edureka.scala
import scala.util.control.Breaks._
class Pascal
{
val r,c=0
val matrix=Array.ofDim[Int](r,c) //declare a two-dimensional array
def fun
{
breakable
{
for(r <- 0 until 4 ;c <- 0 until 4)
{
println(matrix(r)(c)=r+c)
if(r>3)break
}
}
}
}
object pas1 extends App
{
val pasobj=new Pascal()
pasobj.fun
}

Answer 1

You are creating an empty array:
val matrix = Array.ofDim[Int](0, 0)
matrix: Array[Array[Int]] = Array()
Since there are no entries, retrieving one fails:
scala> matrix(0)(0)
java.lang.ArrayIndexOutOfBoundsException: 0
And assigning to one fails, as well:
scala> matrix(0)(0) = 0
java.lang.ArrayIndexOutOfBoundsException: 0
You need to declare an array of 4x4 dimension:
val matrix = Array.ofDim[Int](4, 4)
matrix: Array[Array[Int]] = Array(Array(0, 0, 0, 0), Array(0, 0, 0, 0), ...)
Then you can assign successfully:
scala> matrix(3)(3) = 3
And retrieve as well:
scala> matrix(3)(3)
res1: Int = 3

Answer 2

You define an empty array of array of ints, since you declare r,c=0
# val m = Array.ofDim[Int](0, 0)
m: Array[Array[Int]] = Array()
And then in your loop you try to access the elements in that array (which do not exist)
# m(0)(0)
java.lang.ArrayIndexOutOfBoundsException: 0
$sess.cmd5$.<init>(cmd5.sc:1)
$sess.cmd5$.<clinit>(cmd5.sc:-1)
Simply creating an array of arrays does not fill it with values, especially when you set its dimensions as 0. You can set the dimensions higher and you will have a populated array:
# val m2 = Array.ofDim[Int](5, 5)
m2: Array[Array[Int]] = Array(
Array(0, 0, 0, 0, 0),
Array(0, 0, 0, 0, 0),
Array(0, 0, 0, 0, 0),
Array(0, 0, 0, 0, 0),
Array(0, 0, 0, 0, 0)
)
# m2(1)(4)
res7: Int = 0