How to replace xml empty tags using regex

Question

I have a lot of empty xml tags which needs to be removed from string.

 String dealData = dealDataWriter.toString();
 someData = someData.replaceAll("<somerandomField1/>", "");
 someData = someData.replaceAll("<somerandomField2/>", "");
 someData = someData.replaceAll("<somerandomField3/>", "");
 someData = someData.replaceAll("<somerandomField4/>", "");

This uses a lot of string operations which is not efficient, what can be better ways to avoid these operations.

Your string is actually a xml content ? You should use a java xml parser and delete your empty tags with it; it will be more efficiant. — Stéphane Ammar
– Stéphane Ammar, Commented Jan 10, 2018 at 11:20
Also you should specify what exactly you want to remove - are <somerandomField1 />, <somerandomField1></somerandomField1>, <somerandomField1 xsi:nil="true"/>, <somerandomField1 xsi:nil="true"></somerandomField1> empty tags? They are all empty elements. — Pete Kirkham
– Pete Kirkham, Commented Jan 10, 2018 at 11:41

Oneiros · Accepted Answer · 2018-01-10 11:47:38Z

1

I would not suggest to use Regex when operating on HTML/XML... but for a simple case like yours maybe it is ok to use a rule like this one:

someData.replaceAll("<\\w+?\\/>", "");

Test: link

If you want to consider also the optional spaces before and after the tag names:

someData.replaceAll("<\\s*\\w+?\\s*\\/>", "");

Test: link

edited Jan 10, 2018 at 11:47

answered Jan 10, 2018 at 11:22

Oneiros

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10 Comments

Andy G Over a year ago

I would account for a probable space after the nodename with \s? or even \s*

laune Over a year ago

What's the purpose of \\ preceding /?

Oneiros Over a year ago

You're totally right, thanks (OP: do you see how inadeguate can regex be for xml?)

laune Over a year ago

And there's tons of characters except \w that might appear. The hyphen is just one that's popular.

Oneiros Over a year ago

@laune you have to put a backslash to consider a character literally in Regex. Since we're in Java, you have to put an extra backslash for the same reason

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Arjun · Accepted Answer · 2018-01-10 11:32:29Z

0

Try the following code, You can remove all the tag which does not have any space in it.

someData.replaceAll("<\w+/>","");

answered Jan 10, 2018 at 11:32

Arjun

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Kallmanation · Accepted Answer · 2018-01-10 11:35:19Z

0

Alternatively to using regex or string matching, you can use an xml parser to find empty tags and remove them.

See the answers given over here: Java Remove empty XML tags

answered Jan 10, 2018 at 11:35

Kallmanation

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Mubashar · Accepted Answer · 2020-04-17 05:25:10Z

0

If you like to remove <tagA></tagA> and also <tagB/> you can use following regex. Please note that \1 is used to back reference matching group.

// identifies empty tag i.e <tag1></tag> or <tag/>
// it also supports the possibilities of white spaces around or within the tag. however tags with whitespace as value will not match.
private static final String EMPTY_VALUED_TAG_REGEX = "\\s*<\\s*(\\w+)\\s*></\\s*\\1\\s*>|\\s*<\\s*\\w+\\s*/\\s*>";

Run the code on ideone

answered Apr 17, 2020 at 5:25

Mubashar

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