scala..how to check is not a digit on a character

Question

I need to do a char conversion like this: accountNumber => ACCOUNT_NUMBER

Where there is a caps letter, then prefix a underscore. If not, just capitalize the character

I tried like below

scala> "accountNumber".map{ x => x match { case x if x == x.toUpper => "_"+x ; case x if x!= x.toUpper => x.toUpper}}.mkString
res38: String = ACCOUNT_NUMBER

It works, but it works differently when there is a digit in between.

scala> "filler51".map{ x => x match { case x if x == x.toUpper && x.isDigit && true => "_"+x ; case x if x!= x.toUpper => x.toUpper}}.mkString 
res31: String = FILLER_5_1

I'm expecting it to print FILLER51. For this, I tweaked the code as below, but I'm getting an error.

 scala> "filler51".map{ x => x match { case x if x == x.toUpper && !(x.isDigit)   => "_"+x ; case x if x!= x.toUpper => x.toUpper}}.mkString  
scala.MatchError: 5 (of class java.lang.Character)
  at .$line40$$read$$$anonfun$1(<console>:12)
  at .$line40$$read$$$anonfun$1$adapted(<console>:12)
  at $$Lambda$1399/645018917.apply(Unknown Source)
  at ap(StringOps.scala:29)
     ... 28 elided

Ok.. but what is wrong with negating isDigit syntax in my code — stack0114106, Mar 28 '18 at 15:56

Leo C · Answer 1 · 2018-03-28T16:16:30.307

1

You're almost there – just need a catch-all to cover all cases, as your two match cases have not exhausted all possibilities (namely, the case of isDigit):

"thisFiller51".map { x => x match { 
  case x if x == x.toUpper && !x.isDigit => "_" + x
  case x if x != x.toUpper => x.toUpper
  case x => x
} }.mkString  
// res1: String = THIS_FILLER51

edited Mar 28 '18 at 16:16

answered Mar 28 '18 at 16:06

Leo C

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score 0 · Answer 2 · edited Mar 29 '18 at 07:27

0

Please use the below approach

scala> "filler51".map(x=>if(x>='A' && x<='Z') '_'.toString+x.toString else x.toString)
                 .mkString
                 .toUpperCase

Result:

res6: String = FILLER51

edited Mar 29 '18 at 07:27

The Archetypal Paul

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answered Mar 28 '18 at 15:47

Manoj Kumar Dhakad

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I hope this will help you! – Manoj Kumar Dhakad Mar 28 '18 at 15:50
Ok.. but what is wrong with negating isDigit syntax in my code – stack0114106 Mar 28 '18 at 16:02
Better not to use explicit comparisons with A and Z if you want it to work with all Unicode lower/upper case. – The Archetypal Paul Mar 29 '18 at 07:29

score 0 · Answer 3 · answered Mar 28 '18 at 16:32

0

Instead of testing for != upper, test for explicitly lower:

"filler51".map {x => x match {case x if x == x.toUpper && !(x.isDigit) => "_" + x; case x if x == x.toLower => x.toUpper}}.mkString

answered Mar 28 '18 at 16:32

user unknown

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scala..how to check is not a digit on a character

3 Answers3