how to ask user input for list of strings

Question

I wanna know how to ask user input for a string. For example:

when user input is asked "lruud" is entered

Enter letters: lruud

and I want it the return should be:

Left
right 
up
up 
down

left = l, right = r, etc.

So basically it should return the result in the order the letters are entered.

The code below is what I have tried where al() is move left, ar() is move right etc

def move(s: String) {
  if(s == "l"){
    al()
  }else if(s == "r"){
    ar()
  }else if(s == "u"){
    au()
  }else if(s == "d"){
    ad()
  }  
}

What have you tried? Show us code that doesn't work so that we can better focus our suggestions. — jwvh
– jwvh, Commented May 12, 2020 at 20:47
def move(s: String) { if(s == "l"){ al() }else if(s == "r"){ ar() }else if(s == "u"){ au() }else if(s == "d"){ ad() } } thats the code — Suraj Odedra
– Suraj Odedra, Commented May 12, 2020 at 20:52
Please edit your question and add the code there. As you can see, SO comments make for terrible code formatting. — jwvh
– jwvh, Commented May 12, 2020 at 20:54
sorry I am new here, havent gotten comfortable with how to use everything. But I edited my question its much clear now — Suraj Odedra
– Suraj Odedra, Commented May 12, 2020 at 21:17

Mario Galic · Accepted Answer · 2020-05-12 21:43:50Z

2

You can read in a string from standard input using

val s = scala.io.StdIn.readLine()

Scala implicitly considers String to be a Scala collection, in particular an IndexedSeq which means you can call standard collections methods on it such as map to transform it. For example

def move(s: Char): String = {
  if (s == 'l') "left"
  else if (s == 'r') "right"
  else if (s == 'u') "up"
  else if (s == 'd') "down"
  else throw new RuntimeException("Bad input")
}

"lruud".map(move)
// res4: IndexedSeq[String] = ArraySeq(left, right, up, up, down)

Mapping over a String reads each Char in the string and passes it to the move method for transformation.

answered May 12, 2020 at 21:43

Mario Galic

48.6k6 gold badges64 silver badges111 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Suraj Odedra Over a year ago

thank you that code works. But now what if instead of the letter "l" being equal to "left" it is equal to a function for example al(). So what I want is if the letter "l" is entered it does the function corresponding to that letter in this case if "l" then does the function al()

Suraj Odedra Over a year ago

I tried replacing "left" with al() but gives an error saying that required string found unit

Mario Galic Over a year ago

@SurajOdedra Then you need to change the return type of move from String to Unit that is def move(s: Char): Unit.

jwvh · Accepted Answer · 2020-05-12 21:45:41Z

2

Here's one way to go about this.

val action :Map[Char,String] =
  Map('d'->"down",'l'->"left",'r'->"right",'u'->"up")
    .withDefault(c => s"$c?")

val moves :Seq[String] =
  io.StdIn.readLine("Enter letters: ").map(c =>action(c.toLower))

println("\ndirections:\n" + moves.mkString("  ","\n  ",""))

testing:

Enter letters: lLdRbu

directions:
  left
  left
  down
  right
  b?
  up

answered May 12, 2020 at 21:45

jwvh

51.3k7 gold badges42 silver badges70 bronze badges

Collectives™ on Stack Overflow

how to ask user input for list of strings

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related