Regex Matching using Matcher and Pattern - regex

Question

I am trying to do regex on a number based on the below conditions, however its returning an empty string
import java.util.regex.Matcher
import java.util.regex.Pattern
object clean extends App {
val ALPHANUMERIC: Pattern = Pattern.compile("^[a-zA-Z0-9]*$")
val SPECIALCHAR: Pattern = Pattern.compile("[a-zA-Z0-9\\-#\\.\\(\\)\\/%&\\s]")
val LEADINGZEROES: Pattern = Pattern.compile("^[0]+(?!$)")
val TRAILINGZEROES: Pattern = Pattern.compile("\\.0*$|(\\.\\d*?)0+$")
def evaluate(codes: String): String = {
var str2: String = codes.toString
var text:Matcher = LEADINGZEROES.matcher(str2)
str2 = text.replaceAll("")
text = ALPHANUMERIC.matcher(str2)
str2 = text.replaceAll("")
text = SPECIALCHAR.matcher(str2)
str2 = text.replaceAll("")
text = TRAILINGZEROES.matcher(str2)
str2 = text.replaceAll("")
}
}
the code is returning empty string for LEADINGZEROES match.
scala> println("cleaned value :" + evaluate("0001234"))
cleaned value :
What change should I do to make the code work as I expect. Basically i am trying to remove leading/trailing zeroes and if the numbers has special characters/alphanumeric values than entire value should be returned null

Answer 1

Your LEADINGZEROES pattern is working correct as
val LEADINGZEROES: Pattern = Pattern.compile("^[0]+(?!$)")
println(LEADINGZEROES.matcher("0001234").replaceAll(""))
gives
//1234
But then there is a pattern matching
text = ALPHANUMERIC.matcher(str2)
which replaces all alphanumeric to "" and this made str as empty ("")
As when you do
val ALPHANUMERIC: Pattern = Pattern.compile("^[a-zA-Z0-9]*$")
val LEADINGZEROES: Pattern = Pattern.compile("^[0]+(?!$)")
println(ALPHANUMERIC.matcher(LEADINGZEROES.matcher("0001234").replaceAll("")).replaceAll(""))
it will print empty
Updated
As you have commented
if there is a code that is alphanumeric i want to make that value NULL
but in case of leading or trailing zeroes its pure number, which should return me the value after removing zeroes
but its also returning null for trailing and leading zeroes matches
and also how can I skip a match , suppose i want the regex to not match the number 0999 for trimming leading zeroes
You can write your evaluate function and regexes as below
val LEADINGTRAILINGZEROES = """(0*)(\d{4})(0*)""".r
val ALPHANUMERIC = """[a-zA-Z]""".r
def evaluate(codes: String): String = {
val LEADINGTRAILINGZEROES(first, second, third) = if(ALPHANUMERIC.findAllIn(codes).length != 0) "0010" else codes
if(second.equalsIgnoreCase("0010")) "NULL" else second
}
which should give you
println("cleaned value : " + evaluate("000123400"))
// cleaned value : 1234
println("alphanumeric : " + evaluate("0001A234"))
// alphanumeric : NULL
println("skipping : " + evaluate("0999"))
// skipping : 0999
I hope the answer is helpful