Extract Drive Letter, java regex

Question

I cannot get this simple regex to work. I need to check to see if the file path includes the drive letter, if it doesn't throw an exception.

if (!arcvalFileFormBean.getTxtFileReview().matches("^([A-Z]):")) {
    status = "MAPPING ERROR: Please submit a file from a mapped drive (i.e. K:\\).";
    request.setAttribute(FairValConstants.status, status);
    throw new InvalidFileMoveException(FairValConstants.MAKE_VALID_SELECTION);
}

When I test the code with this W:\testFolder\testfile_v1234_12_23_2014_1245.pfd it fails, when it should pass. When I test it without the drive letter, but the full path it fails. There is something wrong with my regex. I have tried a few different regexs but nothing has worked.

Thanks for your time.

anubhava · Accepted Answer · 2014-02-03T16:45:54.097

5

Problem is matches("^([A-Z]):")) since String#matches matched full input not just a part of it.

Try this instead to make it match full line:

if (!arcvalFileFormBean.getTxtFileReview().matches("((?i)(?s)[A-Z]):.*")) {

PS: ^ and $ anchors are also not required in String#matches since that is implicit.

(?i) => Ignore case
(?s) => DOTALL (mase DOT match new lines as well)

edited Feb 03 '14 at 16:45

answered Feb 03 '14 at 16:30

anubhava

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`s` flag or maybe `d` flag is more appropriate here, since the file name is allowed to contain `\u0085`, `\u2028` and `\u2029` – nhahtdh Feb 03 '14 at 16:39
You can write it as `(?is)[A-Z]:.*` – nhahtdh Feb 03 '14 at 16:51
Thanks, Yes it can be written as that also, just wanted to be more verbose here for explanation purpose. – anubhava Feb 03 '14 at 16:54

score 5 · Answer 2 · answered Feb 03 '14 at 16:30

5

matches() tests that the whole string matches the regex. So A: will match, but not A:\blabla (and a: neither).

The regex should be something like

^([A-Za-z]):.*$

answered Feb 03 '14 at 16:30

JB Nizet

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`s` flag or maybe `d` flag is more appropriate here, since the file name is allowed to contain `\u0085`, `\u2028` and `\u2029` – nhahtdh Feb 03 '14 at 16:37
I'm not a regex expert. What do you mean by "the s flag"? Where should it be added, and to do what? – JB Nizet Feb 03 '14 at 16:41
By default `.` matches any character *except* `\n`, `\r`, `\u0085`, `\u2028`, `\u2029`. `s` flag makes `.` matches any character (no exception), while `d` flag makes `.` matches any character *except* only `\n`. You can use inline flag by `(?s)` or `(?d)` – nhahtdh Feb 03 '14 at 16:43

score 0 · Answer 3 · answered Feb 03 '14 at 16:32

0

matches checks if entire string matches regex. What you are looking for is find from Matcher class.

Pattern p = Pattern.compile(yourRegex);//you can save it as static field to reuse this regex

if (p.matcher(yourInput).find()){
    //do your job
}

answered Feb 03 '14 at 16:32

Pshemo

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Extract Drive Letter, java regex

3 Answers3