Regex pattern to detect payload.* pattern - regex

Question

I want to validate all strings that have 'payload.*' i.e the string must start with 'payload' followed by a period (.) and followed by minimum 1 character.
example :-
Input1 :- payload.Hello Output1 :-> Valid
Input2 :- Hipayload.Hello Output1 :-> InValid
Input3 :- payload.H Output1 :-> Valid
Input4 :- payload. Output1 :-> InValid

Answer 1

You can use x.matches(y) (where x and y are both Strings) to match against a Regex pattern in Scala (or use "raw" Strings):
scala> val regex: String = "^payload\\..+"
regex: String = ^payload\..+
scala> val regexAltRaw: String = raw"^payload\..+"
regexAltRaw : String = ^payload\..+
scala> val regexAltTripleQuotes: String = """^payload\..+"""
regexAltTripleQuotes : String = ^payload\..+
scala> "".matches(regex)
res0: Boolean = false
scala> "payload.Hello".matches(regex)
res1: Boolean = true
scala> "Hipayload.Hello".matches(regex)
res2: Boolean = false
scala> "payload.H".matches(regex)
res3: Boolean = true
scala> "payload.".matches(regex)
res4: Boolean = false
To explain the pattern:
^payload - starts with "payload"
\\. - "." literally (without using "raw" Strings, Scala requires you to use double back-slashes to escape rather than single slashes like you would in normal Regex)
.+ - any character, one or more times

Answer 2

In order to avoid validation of input payload.. you can use foolowing regex:
^payload\.[^.]+$

Answer 3

Input Array:
val ar = Array("payload.Hello","Hipayload.Hello","payload.H","payload.")
Regex String:
val p = """^payload\..{1,}"""
In Scala REPL:
scala> val ar = Array("payload.Hello","Hipayload.Hello","payload.H","payload.")
ar: Array[String] = Array(payload.Hello, Hipayload.Hello, payload.H, payload.)
scala> val p = """^payload\..{1,}"""
p: String = ^payload\..{1,}
Test:
scala> ar.map(x=>if(x.matches(p))"Valid" else "InValid")
res3: Array[String] = Array(Valid, InValid, Valid, InValid)