Converting command line argument key=value pair to Map in scala

Question

in my main program i receive inputs like - key1=value1 key2=value2

Now what I want is to create a map out of it. I know the imperative way of doing this where I would get Array[String] that can be foreach and then split by "=" and then key and value can be used to form a Map.

is there a good functional and readable way to achieve this? Also It will be great if I can avoid mutable Map and I want to avoid initial Dummy value initialization.

  def initialize(strings: Array[String]): Unit = {
    val m = collection.mutable.Map("dummy" -> "dummyval")
    strings.foreach(
      s => {
        val keyVal:Array[String] = s.split("=")

        m += keyVal(0) -> keyVal(1)

      })
    println(m)
  }

score 5 · Accepted Answer · edited May 23 '17 at 12:02

5

you can just use toMap().

However, converting from array to tuple is not quite trivial: How to convert an Array to a Tuple?

scala> val ar = Array("key1=value1","key2=value2")
ar: Array[String] = Array(key1=value1, key2=value2)

scala> ar.collect(_.split("=") match { case Array(x,y) => (x,y)}).toMap
res10: scala.collection.immutable.Map[String,String] = Map(key1 -> value1, key2 -> value2)

Maybe you have to call Function.unlift for intellij

val r = ar.collect(Function.unlift(_.split("=") match { case Array(x, y) => Some(x, y)})).toMap

edited May 23 '17 at 12:02

Community

1
1

answered Oct 21 '16 at 06:44

ymonad

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error coming "can not resolve reference collect to such signature" in intellij. – Mohammad Adnan Oct 21 '16 at 06:48
more precise error - type mismatch, expected PartialFunction[String, NotInferedB], actual (Any) => (T,T) – Mohammad Adnan Oct 21 '16 at 06:52
yes.. thanks so much. i wonder if intellij can fix this issue. – Mohammad Adnan Oct 21 '16 at 07:18

score 2 · Answer 2 · answered Oct 21 '16 at 06:49

2

similar to above but using only 'map'

ar.map(_.split("=")).map(a=>(a(0), a(1))).toMap

answered Oct 21 '16 at 06:49

hi_my_name_is

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then its your IDE, try using File->Invalidates caches and restart. You can always verify one line solutions in scala repl just to be sure your IDE is not messing with you :) – hi_my_name_is Oct 21 '16 at 06:56

score 0 · Answer 3 · answered Oct 21 '16 at 06:55

0

You can use Scopt to do the command line argument parsing in a neat way.

answered Oct 21 '16 at 06:55

Aravindh S

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u don't always have luxury to use any open source as per your convenience :) – Mohammad Adnan Oct 21 '16 at 06:57
It was a suggestion my friend. :) – Aravindh S Oct 21 '16 at 07:00

Converting command line argument key=value pair to Map in scala

3 Answers3