java regex matcher error

Question

I am trying to find the regex of the following link http://anythingbutrbitrary.blogspot.in/search?updated-max=2014-02-10T11:58:00-08:00&max-results=1.

My code with regex http://anythingbutrbitrary.blogspot.in/search?updated-max=\\d{4}-\\d{2}-d{2}T\\d{2}:\\d{2}:\\d{2}-\\d{2}-\\d{2}&max-results=\\d{1} returning false. What is wrong with the regex? My java code is as follows:

String regex= "http://anythingbutrbitrary.blogspot.in/search?updated-max=\\d{4}-\\d{2}-d{2}T\\d{2}:\\d{2}:\\d{2}-\\d{2}-\\d{2}&max-results=\\d{1}";
Pattern p=Pattern.compile(Pattern.quote(regex));
Matcher m = p.matcher("http://anythingbutrbitrary.blogspot.in/search?updated-max=2014-02-10T11:58:00-08:00&max-results=1");
System.out.println(m.lookingAt());

Please help. Thanks

anubhava · Accepted Answer · 2014-05-13 07:34:57Z

2

Couple of mistakes in your regex.

You are calling Pattern.quote which will make your regex literal.
Meta characters like dot and ? need to be escaped to \\. and \\?

EDIT: After looking at your regex I found that is also wrong. Use this regex:

String regex="http://anythingbutrbitrary\\.blogspot\\.in/search\\?updated-max=\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}-\\d{2}:\\d{2}&max-results=\\d";

edited May 13, 2014 at 7:34

answered May 13, 2014 at 7:27

anubhava

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2 Comments

Nicolai Krüger Over a year ago

You also need to escape the backslash \/

anubhava Over a year ago

No that is not needed in Java.

Bohemian · Accepted Answer · 2014-05-13 07:35:48Z

1

Couple of things:

escape the ? with a backslash, otherwise it means "1 or 0 of previous term", so you're losing a character, which is why it's not matching (technically you should escape the dots too, but hardly worth it)
use String.matches() instead - it's easier to use

Try this:

String regex = "http://anythingbutrbitrary.blogspot.in/search\\?updated-max=\\d{4}-\\d{2}-d{2}T\\d{2}:\\d{2}:\\d{2}-\\d{2}-\\d{2}&max-results=\\d";
if (urlStr.matches(regex))

answered May 13, 2014 at 7:35

Bohemian♦

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Community · Accepted Answer · 2020-06-20 09:12:55Z

1

Pattern.quote() may not do what you want it to do...

From the online API:

This method produces a String that can be used to create a Pattern that would match the string s as if it were a literal pattern.

Metacharacters or escape sequences in the input sequence will be given no special meaning.

In addition, the lookingAt() javadoc says (emphasis mine):

Returns: true if, and only if, a prefix of the input sequence matches this matcher's pattern

Few minor mistakes in your regex, surrounded by two stars:

http://anythingbutrbitrary**.**blogspot**.**in/search**?**updated-max=\\d{4}-\\d{2}-**d{2}**T\\d{2}:\\d{2}:\\d{2}-\\d{2}**-**\\d{2}&max-results=\\d{1}

Should escape period (otherwise you'll match any character. Doesn't really matter for this specific case, though)
Same as 1.
Escape the question mark (it means "one or none of the preceding character", which certainly won't produce correct results)
Forgot to escape d (should be \\d)
dash instead of colon

You should make your pattern code by doing Pattern.compile(regex);. Right now, you're making a pattern that matches regex as is, with escapes and metacharacters ignored. In addition, I think you might want m.matches() rather than m.lookingAt()...

edited Jun 20, 2020 at 9:12

CommunityBot

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answered May 13, 2014 at 7:29

awksp

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1 Comment

awksp Over a year ago

I thought that's what I said? Was I not clear enough?

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