正则表达式Java模式

Question

I should match two numbers bigger than 0 separated from a whitespace

^\\d+?\\s\\d+?$

I tried that but it clearly doesn't work then I should also match a string that begins with # and ends with # and inside there should be a fixed amount of char, that can be any char, determined by a variable w - 2.

String regex = "#.{" + (w - 2) + "}$";

return Pattern.matches(regex, stringToMatch );

tried that but doesnt work.

Answer 1

The most efficient way (I know ;) to match a non-zero number, while asserting it's a valid number and allowing for leading zeroes, is

\d*[1-9]\d*

This makes sure all tested characters are digits and at least one of them isn't a zero.

So your first declaration should be something like

String regex = "^\\d*[1-9]\\d*\\s\\d*[1-9]\\d*$";

(You could do similar things with look-around, but they're less effective - especially for longer numbers.)

---

As for the second part of your question, as mentioned in comments, you've forgotten the ending # . If it's allowed to be preceded and followed by other text:

String regex = "#.{" + (w - 2) + "}#";

If it should be the only text:

String regex = "^#.{" + (w - 2) + "}#$";

Hope this helps.

Regards