CODEWITHSUNDEEP
javaregexdigits
Dron4K
Dron4K

Reputation: 473

Java regular expression for digits and dashes

I need a regular expression which matches lines with only 4(four) hyphens and 13 digits(0-9). The order is undefined. I have regex like: 

^([0-9\u2013-]{17})$

But, when I receive strings as

----123456789---- or 1-2-3-4-5-6-7-8-9

matching is true but it must be false for me.

Could you please explain what I need use in order to matches were only with strings like 123-345-565-45-67 or 123-1-34-5435-45- or ----1234567890123 etc?

Upvotes: 3

Views: 1867

Answers (1)

Gurmanjot Singh
Gurmanjot Singh

Reputation: 10360

Try this regex:

^(?=(?:[^-]*-){4}[^-]*$)(?=(?:\D*\d){13}\D*$).*$

Click for Demo

Explanation:

  • ^ - asserts the start of the line
  • (?=(?:[^-]*-){4}[^-]*$) - positive lookahead to make sure that there are only 4 occurrences of - present in the string
  • (?=(?:\D*\d){13}\D*$) - positive lookahead to make sure that there are 13 occurrences of a digit present in the string
  • .* - once the above 2 lookaheads are satisified, match 0+ occurrences of any character except a newline character
  • $ - asserts the end of the line

Escape \ with another \ in JAVA

Upvotes: 4

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