I have the following code:
val copyA = a.clone
copyA(0)(0) = 1
println("a(0)(0): " + a(0)(0))
This prints:
a(0)(0): 1
If I change it to this:
val copyA = a.clone
println("a(0)(0): " + a(0)(0))
It prints:
a(0)(0): 0
So why is a affected by a change in copyA?
How can I make it such that changes in copyA don't affect a?
Mutating the cloned 1D array instance won't change the original instance and vice-versa,
example,
scala> val original = Array(100, 200)
original: Array[Int] = Array(100, 200)
scala> val cloned = original.clone
cloned: Array[Int] = Array(100, 200)
mutating cloned array does not affect original array,
scala> cloned(0) = 5000
scala> original(0) //still the same value
res36: Int = 100
mutating original array does not affect cloned array,
scala> original(0) = 8888
scala> cloned(0) // still the same
res38: Int = 5000
But its different regarding 2D array, because each array inside is a ref and has to be deep cloned
scala> val original = Array.ofDim[Int](2,2)
original: Array[Array[Int]] = Array(Array(0, 0), Array(0, 0))
scala> original.foreach {col => println(col)}
[I@745e24c4
[I@42c6563f
deep cloning 2D array
scala> val cloned = original.map(_.clone)
cloned: Array[Array[Int]] = Array(Array(0, 0), Array(0, 0))
scala> original(0)(0) = 5000
scala> cloned(0)(0)
res43: Int = 0
//changing cloned does not change original array
scala> cloned(0)(0) = 8888
scala> original(0)(0)
res48: Int = 5000
You cloned the array. You didn't clone whatever was in the array.
In your code, you are not manipulating the array. You are getting an element out of the array and manipulating that object. The arrays are completely irrelevant here.
