Find file with a pattern

Question

I try to search file with a name like: ENV20120517 every thing you what and finish by .DAT

So i set pattern to: "ENV20120517*.*DAT".

 public boolean accept(File dir, String name) {
    if (pattern != null) {
        return name.matches(pattern);
    }
    return false;
 }

Why with the previous pattern, i get true for: name = "ENV20120516053518.DAT" ?

score 4 · Accepted Answer · edited May 23 '17 at 12:27

4

String.matches() takes a regular expression, and not a glob pattern.

It so happens that ENV20120517*.*DAT is a valid regex. It does, however, have a different meaning to what you're expecting: it matches any string that starts with ENV2012051 and ends in DAT (the .* matches anything, and the 7* is effectively a no-op).

The following regex is equivalent to the pattern in your question ENV20120517.*[.].*DAT

For some ideas on how to do glob matching in Java, see Is there an equivalent of java.util.regex for "glob" type patterns?

edited May 23 '17 at 12:27

Community

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answered May 24 '12 at 08:33

NPE

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`DAT` must be at the end: Java's `matches(...)` validates the entire input string. – Bart Kiers May 24 '12 at 08:43
This answer might help a lot of people that are not aware of the functionality of `String.matches()`. +1 – brimborium May 24 '12 at 08:44
with pattern = ENV20120517 and name.startsWith(pattern) && name.endsWith("DAT"); that work fine... but is there a better way to resolve the problem? – robert trudel May 24 '12 at 08:56
1

@robert: The pattern `ENV20120517.*.DAT` would be the equivalent to the glob pattern `ENV20120517*.DAT`. – brimborium May 24 '12 at 09:00
don't forget to escape the second '.' in the regex – fabregaszy May 24 '12 at 09:12

Liu guanghua · Answer 2 · 2012-05-24T10:37:50.737

0

The parttern should be "ENV20120517.*DAT", because "ENV20120517*.*DAT", the first * matches 0 or more 7 char, so"ENV20120516053518.DAT".matches("ENV20120517*.*DAT") is true.

edited May 24 '12 at 10:37

answered May 24 '12 at 08:40

Liu guanghua

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if i put: ENV20120517.*DAT, there are no file found – robert trudel May 24 '12 at 08:51
you run: String pattern = "ENV20120517.*DAT"; for (int i = 100000; i < 1000000; i++) { String fileName = "ENV20120517" + i + ".DAT"; if (!fileName.matches(pattern)) { System.out.println(fileName + " doesn't match pattern: " + pattern); } } – Liu guanghua May 25 '12 at 01:18

score 0 · Answer 3 · answered May 24 '12 at 09:45

0

Try

pattern = "ENV20120517.*\\.DAT"

Or more strictly:

pattern = "^ENV20120517.*\\.DAT$"

answered May 24 '12 at 09:45

fabregaszy

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Find file with a pattern

3 Answers3