Regex to find three or more repeated number except 999 in Java

Question

Need help to stop user from entering phone number with three or more repeated digits except 999.

Phone number could be 10 digit to 25 digit.

Bad Input:

Exception:

I tried --> \b(\d)\3+\b but looks that is not right.

Have already tried some pattern? If so, would you include it in your question please. — bobble bubble, Jun 25 '22 at 01:57
I looked at https://stackoverflow.com/questions/6507982/regex-to-find-repeating-numbers and patterns like \b(\d)\1+\b but didnt help — Avatar Girase, Jun 25 '22 at 01:59
I find the requirement strange. Is this really what you want? Why can't there be 3 repeated digits in a phone number? — Henry, Jun 25 '22 at 02:09

bobble bubble · Accepted Answer · 2022-06-25T02:21:06.187

4

Have a try with

^(?:([0-8])(?!\1\1)|9){10,25}$

Or something like this

^(?!.*?([0-8])\1\1)\d{10,25}$

Digits are captured in first group. A negative lookahead is used to check for backrefernce \1.

edited Jun 25 '22 at 02:21

answered Jun 25 '22 at 02:04

bobble bubble

Thank You @bobble bubble. The second one helps. what if instead 0f 999 the allowed digits are 888 – Avatar Girase Jun 25 '22 at 02:29
1

@AvatarGirase Welcome:) For `888` allowed like this: [`^(?!.*?([0-79])\1\1)\d{10,25}$`](https://regex101.com/r/VYA1uI/1) or first one: [`^(?:(\d)(?!\1\1)|8){10,25}$`](https://regex101.com/r/qujU6N/1) (a bit simplified/shortened) – bobble bubble Jun 25 '22 at 02:32
Works like a charm @bobble bubble. Thank You for the lightning fast response. Do you have any book that I can take a look or any suggestion from where I should learn this. – Avatar Girase Jun 25 '22 at 02:38
1

yw:) actually I learned the most while working a lot with regexes and here by answering and studying but if you like books: [Jeffrey Fridl - Mastering Regular Expressions](https://www.amazon.de/Mastering-Regular-Expressions-Jeffrey-Friedl/dp/0596528124) - websites: [RexEgg](https://www.rexegg.com/), [Regular-Expressions.info](https://www.regular-expressions.info/) and for testing [Regex101](https://regex101.com/), [Regexstorm](http://regexstorm.net/tester) (.NET), [RegexPlanet](https://www.regexplanet.com/advanced/java/index.html) (Java) – bobble bubble Jun 25 '22 at 02:46
could you please help me on this https://stackoverflow.com/questions/72957182/regex-to-stop-user-from-entering-first-three-repeated-digit-except-888 – Avatar Girase Jul 12 '22 at 19:06

score 1 · Answer 2 · edited Jun 25 '22 at 09:23

1

Please check this.

([0-8])\1{2}

I think this can help you. This is simpler and faster. If you have other questions, please. Good luck.

edited Jun 25 '22 at 09:23

The fourth bird

answered Jun 25 '22 at 02:11

2

Read the question carefully. The OP wants to match 3 digits **except** "999". Your matches 3 digits **including** "999". Also presenting your answer as a screenshot is unhelpful for programmers who have impaired vision. – Stephen C Jun 25 '22 at 02:21
ok. Please use ([0-8])\1{2} – Jun 25 '22 at 02:34

2 Answers2