正则表达式，不包含两个或多个连续的逗号或连字符，并且在数字之间最多包含一个连字符

Question

I have scenario to validate number range, it can be multiple range or single number.

Ex number 1 to 10 can be written as (1-3,4,5-8,9,10) here 1-3 indicates rage (1,2,3) I have tried java regex :

Pattern.matches("^[0-9][0-9,-]*,[0-9,-]*[0-9]$","11,131-132-134,45,12--10,,10");

this pattern allows consecutive hyphen and comma,

Valid Input

1) 1-3,4,5-8,9,10
2) 1-3,4-5,6-10
3) 1,2,3,4,5
4) 1,2-5,6

Invalid Input

1) ,2,3,4-10,
2) -2,3,4-10-
3) 2,3,,4-10
4) 2,3,4--10
5) 2,3,4-6-10 (Invalid range)

can someone suggest how to check the comma and hyphen should not appear two times consecutively, start and end with number, range should not repeat (4-8-10)

Answer 1

This should be the regex you want:

^\\d+(-\\d+)?(,\\d+(-\\d+)?)*$

It checks for the following sequence:

\\\\d+ : One or more digits

(-\\\\d+)? : An optional sequence of hyphen followed by one or more digits

(,\\\\d+(-\\\\d+)?)* : Zero or more occurrence of a comma followed by one or more digits followed by an optional sequence of hyphen followed by one or more digits

As the regex looks for a digit at the beginning, a string starting with hyphen or comma will not be allowed.

As it looks for a digit to be immediately followed by a hyphen and comma, a string having consecutive hyphens or commas, a hyphen immediately followed by a comma or the reverse would not be allowed.

As the ? in (-\\\\d+)? allows exactly zero or one occurrence of the (-\\\\d+) sequence, a range like 1-2-3 will not be matched.

If you don't need to allow a single number alone, replace the * in ^\\\\d+(-\\\\d+)?(,\\\\d+(-\\\\d+)?)*$ with + .

Answer 2

A repeated group is a simple way to validate a string of a repeating sequence:

(?:\\d+(?:-\\d+)?,)+(?:\\d+(?:-\\d+)?$)

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