How to remove a specific special character pattern from a string

Question

I have a string name s,

String s = "<NOUN>Sam</NOUN> , a student of the University of oxford , won the Ethugalpura International Rating Chess Tournament which concluded on Dec.22 at the Blue Olympiad Hotel";  

I want to remove all <NOUN> and </NOUN> tags from the string. I used this to remove tags,

s.replaceAll("[<NOUN>,</NOUN>]","");

Yes it removes the tag. but it also removes letter 'U' and 'O' characters from the string which gives me following output.

 Sam , a student of the niversity of oxford , won the Ethugalpura International Rating Chess Tournament which concluded on Dec.22 at the Blue lympiad Hotel

Can anyone please tell me how to do this correctly?

Answer 1

Try:

s.replaceAll("<NOUN>|</NOUN>", "");

In RegEx, the syntax [...] will match every character inside the brackets, regardless of the order they appear in. Therefore, in your example, all appearances of "<", "N", "O" etc. are removed. Instead use the pipe (|) to match both "<NOUN>" and "</NOUN>".

The following should also work (and could be considered more DRY and elegant) since it will match the tag both with and without the forward slash:

s.replaceAll("</?NOUN>", "");

Answer 2

String.replaceAll() takes a regular expression as its first argument. The regexp:

"[<NOUN>,</NOUN>]"

defines within the brackets the set of characters to be identified and thus removed. Thus you're asking to remove the characters <,>,/,N,O,U and comma.

Perhaps the simplest method to do what you want is to do:

s.replaceAll("<NOUN>","").replaceAll("</NOUN>","");

which is explicit in what it's removing. More complex regular expressions are obviously possible.