Question:
I get this issue for several hours.

Why (HP)(A)->H does NOT match [^a-zA-Z0-9]A[^a-zA-Z0-9] in Kotlin?

regexr website

Expression1

/[^a-zA-Z0-9]A[^a-zA-Z0-9]/g

Text
(HP)(A)->H

Result
(A)

Expression2

/[^a-zA-Z0-9]A[^a-zA-Z0-9]/gy

Text
(HP)(A)->H

Result

no result

Regex class in Kotlin

In VSC

Code

test1.kt

fun exactlyMatch(target:String,entryForReplacement:Pair<String,String>){
    val nonLetterOrDigit = "[^a-zA-Z0-9]"
    val (key,value) = entryForReplacement
    val keyRegexString = nonLetterOrDigit + key + nonLetterOrDigit
    val keyRegEx = Regex(keyRegexString)
    val matched = keyRegEx.matches(target)
 println("target:${target},key:${key},value:${value},keyRegEx.pattern:${keyRegEx.pattern},matched:${matched}")
}
fun main(){
    val target = "(HP)(A)->H"
    val mapForReplacement : Map<String,String> = mapOf("A" to "Aura:Green","HP" to "HP:75","H" to "healthStatus")
    val mapForReplacementList = mapForReplacement.toList()
    println("mapForReplacementList:${mapForReplacementList}")

    var entryForReplacement: Pair<String,String>
    for(entryForReplacement in mapForReplacementList){
        exactlyMatch(target,entryForReplacement)
    }   
}

Result after execution

    PS C:Users{USERNAME}OneDrive桌面TibaMeKotlinTHE BIG NERD RANCH GUIDECH3> kotlinc test1.kt -include-runtime -d test1.jar
    PS C:Users{USERNAME}OneDrive桌面TibaMeKotlinTHE BIG NERD RANCH GUIDECH3> java -jar test1.jar 
    mapForReplacementList:[(A, Aura:Green), (HP, HP:75), (H, healthStatus)]
    target:(HP)(A)->H,key:A,value:Aura:Green,keyRegEx.pattern:[^a-zA-Z0-9]A[^a-zA-Z0-9],matched:false
    target:(HP)(A)->H,key:HP,value:HP:75,keyRegEx.pattern:[^a-zA-Z0-9]HP[^a-zA-Z0-9],matched:false
    target:(HP)(A)->H,key:H,value:healthStatus,keyRegEx.pattern:[^a-zA-Z0-9]H[^a-zA-Z0-9],matched:false

[]
(https://i.sstatic.net/oJ2amRsA.png)

In Kotlin online active shell

Code

fun exactlyMatch(target:String,entryForReplacement:Pair<String,String>){
    val nonLetterOrDigit = "[^a-zA-Z0-9]"
    val (key,value) = entryForReplacement
    val keyRegexString = nonLetterOrDigit + key + nonLetterOrDigit
    val keyRegEx = Regex(keyRegexString)
    val matched = keyRegEx.matches(target)
      println("target:${target},key:${key},value:${value},keyRegEx.pattern:${keyRegEx.pattern},matched:${matched}")
}

fun main(){
    val target = "(HP)(A)->H"
    val mapForReplacement : Map<String,String> = mapOf("A" to "Aura:Green","HP" to "HP:75","H" to "healthStatus")
    val mapForReplacementList = mapForReplacement.toList()
    println("mapForReplacementList:${mapForReplacementList}")

    var entryForReplacement: Pair<String,String>
    for(entryForReplacement in mapForReplacementList){
        exactlyMatch(target,entryForReplacement)
    }   
}

main()

Result after execution

    mapForReplacementList:[(A, Aura:Green), (HP, HP:75), (H, healthStatus)]
    target:(HP)(A)->H,key:A,value:Aura:Green,keyRegEx.pattern:[^a-zA-Z0-9]A[^a-zA-Z0-9],matched:false
    target:(HP)(A)->H,key:HP,value:HP:75,keyRegEx.pattern:[^a-zA-Z0-9]HP[^a-zA-Z0-9],matched:false
    target:(HP)(A)->H,key:H,value:healthStatus,keyRegEx.pattern:[^a-zA-Z0-9]H[^a-zA-Z0-9],matched:false

[]

Other info

IDE: VSC

Kotlin plugin: []

What I tried?

1. I have test these expression in regexr website.

2. Kotlin docs

Also, I visit Kotlin API reference to know how to use them.

• Regex class
  Regex class

• matches method in Regex class