ReplaceAll regex in xml string

Question

I'm trying to manually add some prefixes to my xml string, for this I need a particular java expression that I just can't seem to find, basically this my string:

 <?xml version="1.0" encoding="UTF-8"?>
<mediabericht xmlns:mb="http://www.mediabericht.org"><inhoud>Randominhoud 22</inhoud><netwerk>Twitter</netwerk><datum>1408625886036</datum><film>Gladiator</film></mediabericht>

I want to add prefixes to my elements, so it should look like this:

<?xml version="1.0" encoding="UTF-8"?>
    <mb:mediabericht xmlns:mb="http://www.mediabericht.org"><mb:inhoud>Randominhoud 22</mb:inhoud><mb:netwerk>Twitter</mb:netwerk><mb:datum>1408625886036</mb:datum><mb:film>Gladiator</mb:film></mb:mediabericht>

I want to do a few replaceall's but so far I had no luck

The first regex I need to solve is < but not <? or </ and use the replaceAll function to replace these by <mb: (the prefix)

Then the second replacement I've handled:

String prefixedString = xmlString.replaceAll("</", "</mb:");

i can't find the differences in the input and the expected output. — Avinash Raj, Aug 21 '14 at 13:08
Apologies I didn't edit the second one, it should have the prefixes — Robin-Hoodie, Aug 21 '14 at 13:10
The proper way to do this is with a parse of the XML tree, not with a regex. — tripleee, Aug 22 '14 at 06:25
I know, but I asked this question on stackoverflow before with no answers, so I figured I'd just do this the dirty way — Robin-Hoodie, Aug 22 '14 at 07:38

score 1 · Accepted Answer · answered Aug 21 '14 at 13:05

1

The first regex I need to solve is < but not <? or </ and use the replaceAll function to replace these by <mb: (the prefix)

This can be solved using look-ahead:

String prefixedString = xmlString.replaceAll("<(?![/?])", "<mb:");

answered Aug 21 '14 at 13:05

Keppil

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After replacing this error it finally worked, thank you so much! – Robin-Hoodie Aug 21 '14 at 13:12

Braj · Answer 2 · 2014-08-21T13:25:54.123

1

You can try with Lookaround

The Lookaround (zero length assertions) actually matches characters, but then gives up the match, returning only the result: match or no match.

<(?!\/|\?)

Replacement : <mb:

OR

(?<=<)(?!\/|\?)

Replacement : mb:

Online demo

Patten explanation:

  (?<=                     look behind to see if there is:
    <                        '<'
  )                        end of look-behind
  (?!                      look ahead to see if there is not:
    \/                       '/'
   |                        OR
    \?                       '?'
  )                        end of look-ahead

Sample code:

System.out.println("<abc></abc>".replaceAll("(?<=<)(?!\\/|\\?)", "mb:"));

OR simply use <\b as suggested by @Avinash Raj in below comments where \b is used as word boundary.

System.out.println("<abc></abc>".replaceAll("<\\b", "<mb:"));

edited Aug 21 '14 at 13:25

answered Aug 21 '14 at 13:07

Braj

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Thank you for the explanation, I should really spend an afternoon learning patterns, so far I've always looked 'em up or asked for them on stackoverflow – Robin-Hoodie Aug 21 '14 at 13:13
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@user You could simply use this `(?<=<)\b` http://regex101.com/r/oE7rZ9/3 – Avinash Raj Aug 21 '14 at 13:16
@AvinashRaj yes, that's also correct. Nice one. OR keep it simple `<\b` – Braj Aug 21 '14 at 13:17

score 1 · Answer 3 · answered Aug 21 '14 at 13:14

1

You can do everything with only one regexp:

String prefixedString = xmlString.replaceAll("(</?)([^?])", "$1mb:$2");

will correctly replace the opening and closing tags (and ignore the <?xml> tag) in only one replaceAll() call.

answered Aug 21 '14 at 13:14

Florent Bayle

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EDIT: Nvm this works, thanks, that makes it even more simple – Robin-Hoodie Aug 21 '14 at 13:18

ReplaceAll regex in xml string

3 Answers3