Scala convert Array of string to List of Integers

Question

How to convert array of string to list of integers using val. I am using below code to do this

object ArraytoListobj {
  def main(args :Array[String]) {
    val intList :List[Int] =  args.toList
    println(intList)
  } 
}

When trying to compile the programme, I am getting below error.

  scala:3:  error: type mismatch;
  found   : List[String]
  required: List[Int]
  val intList :List[Int] =  args.toList
one error found

args.map(_.toInt).toList but it will throw if any String contains non-digit characters. — jwvh
– jwvh, Commented Feb 26, 2019 at 8:23

Raman Mishra · Accepted Answer · 2019-02-26 10:14:22Z

7

You can just do that, if you are sure all the element in the args are going to be Int.

val strToInt = args.map(_.toInt).toList
println(strToInt)

answered Feb 26, 2019 at 10:14

Raman Mishra

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3 Comments

Raman Mishra Over a year ago

I would love to improve my answer, if the person who downvoted let me know the problem.

Yuval Itzchakov Over a year ago

Not the downvoter, but I guess this misses the fact that there may be strings in the array which are not parseable to an Int.

Raman Mishra Over a year ago

I explicitly mentioned that if you are sure that all the elements are Int so i don’t think that should be the reason

Yuval Itzchakov · Accepted Answer · 2020-01-11 16:35:18Z

6

Edit:

As of Scala 2.13.0, you can write:

val listOfInts: List[Int] = args.flatMap(_.toIntOption)

For Scala < 2.13

If you want to convert and discard any non Int matching Strings:

val listOfInts: List[Int] = args.flatMap(i => Try(i.toInt).toOption).toList

edited Jan 11, 2020 at 16:35

answered Feb 26, 2019 at 8:27

Yuval Itzchakov

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2 Comments

Azmath Shaik Over a year ago

Thanq @ Yuval. I will try to implement this

Seth Tisue Over a year ago

in Scala 2.13 (which is still in milestones), you will be able to cut Try out of it and just args.flatMap(_.toIntOption)

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