Java // No match with RegExp and square brackets

Question

I have a string like

Berlin -> Munich [label="590"]

and now I'm searching a regular expression in Java that checks if a given line (like above) is valid or not. Currently, my RegExp looks like \\w\\s*->\\s*\\w\\s*\\[label=\"\\d\"\\]" However, it doesn't work and I've found out that \\w\\s*->\\s*\\w\\s* still works but when adding \\[ it can't find the occurence (\\w\\s*->\\s*\\w\\s*\\[). What I also found out is that when '->' is removed it works (\\w\\s*\\s*\\w\\s*\\[)

Is the arrow the problem? Can hardly imagine that. I really need some help on this.

Thank you in advance

score 1 · Answer 1 · answered May 24 '14 at 08:42

1

Try this

 String message = "Berlin -> Munich [label=\"590\"]";
 Pattern p = Pattern.compile("\\w+\\s*->\\s*\\w+\\s*\\[label=\"\\d+\"\\]");
 Matcher matcher = p.matcher(message);
 while(matcher.find()) {
      System.out.println(matcher.group());
 }

You need to much more than one token of characters and numbers.

answered May 24 '14 at 08:42

Badr Ghatasheh

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Why the while loop? It will parse some funny-looking strings in `message`. A single test with `matcher.matches()` should be all that's required. – laune May 24 '14 at 08:54
@laune this is a testing code, to make sure your regular expression is not matching those funny groups, not that it will do in this case. – Badr Ghatasheh May 24 '14 at 09:04

laune · Accepted Answer · 2014-05-24T08:55:45.947

1

This is the correct regular expression:

"\\w+\\s*->\\s*\\w+\\s*\\[label=\"\\d+\"\\]"

What you report about matches and non-matches of partial regular expressions is very unlikely, not possible with the Berlin/Munich string.

Also, if you are really into German city names, you might have to consider names like Castrop-Rauxel (which some wit has called the Latin name of Wanne-Eickel ;-) )

edited May 24 '14 at 08:55

answered May 24 '14 at 08:47

laune

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Ok, so the + after \\w did the trick. But what do I need them for? If I'm not mistaken + means "occurs one or several times" and just \\w "one time". But the words in the example above consist of just one word, so why doesn't \\w work? – Andy May 24 '14 at 10:23
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@Andy \w is a word character, not a whole word – Ron Rosenfeld May 24 '14 at 12:30

Java // No match with RegExp and square brackets

2 Answers2