用于数字和短划线的Java正则表达式

Question

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?

Answer 1

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