Scala Patch function

Question

object TestScala {
def main(args: Array[String]): Unit = {
val mainList = List(3, 2, 1)
mainList.patch(1, Seq(5), 0)
println("mainList-->"+mainList)
 }
}

The output is mainList-->List(3, 2, 1) not expected one

I am expecting 3,5,2,1

Answer 1

Scala List is immutable. Assign it to variable and it will produce desired output.

object TestScala {
def main(args: Array[String]): Unit = {
var mainList = List(3, 2, 1)
mainList  = mainList.patch(1, Seq(5), 0)
println("mainList-->"+mainList)
 }
}