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)}
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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
