Regex Java Discrepancy

Question

I need to verify a password using reqex. I have written one and tested it in this checker and it works: http://www.nvcc.edu/home/drodgers/ceu/resources/test_regexp.asp

But when I add it to my Java application, it fails.

Regex in regex checker:(\D+)(\d+)(\D+)(.*)

Regex in java: (\\D+)(\\d+)(\\D+)(.*)

Test string: 1Hello2

This passes in the online checker but fails in Java.

Does anyone know why?

I want the regex to match any password that has a number in its middle (can have them at the start and end too).

I need 2 seperate regex: one that matches digits in the middle (pass1word or 1pass1word or 1pass1word) and also a regex that matches a digit at the start or end (1password or password1 NOT pass1word1 because that is in the string category).

It doesn't pass in the online checker, and I know why. Namely, \D means a non-digit character. To match anything with a number in the middle, use something like '.+\d+.*'. — Lev Levitsky
– Lev Levitsky, Commented Mar 28, 2012 at 13:57
@NiklasB, you're right. It must have the same effect though. — Lev Levitsky
– Lev Levitsky, Commented Mar 28, 2012 at 14:07
@Lev: No, even after the edit it wouldn't match 1hello for example, although it's a valid password according to OP. — Niklas B.
– Niklas B., Commented Mar 28, 2012 at 14:08
@NiklasB: ohhh, I misread (misunderstood) your comment. The regex I actually mean is '.+\d.+' (too late to edit the first comment now). Your regex matches any password with a digit in it. Mine matches any with a digit in the middle, which is how I understand the last sentence of the question. — Lev Levitsky
– Lev Levitsky, Commented Mar 28, 2012 at 14:14

AlexR · Accepted Answer · 2012-03-28 14:00:42Z

2

Your regex requres:

not digit (1 or more times) \D+
1 or more digits
One or more non-digits \D+
Any character(s) 0 or more times.

Your example contains

1 Digit
5 non-digits
1 digit

I think it is obvious that it does not match the regex: the first element \D+ fails because digit appears in the beginning.

answered Mar 28, 2012 at 14:00

AlexR

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1 Comment

TheCoder Over a year ago

My solution in the end: Match strong (\\d*)(\\D+)(\\d+)(\\D+)(.*). Match medium: (\\d+)(\\D+)") || (\\D+)(\\d+)") || (\\d+)(\\D+)(\\d+)

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