CODEWITHSUNDEEP
javaregex
arezzo
arezzo

Reputation: 2925

How to modify this regular expression to be case insensitive while searching for curse words?

At the moment, this profanity filter finds darn and golly but not Darn or Golly or DARN or GOLLY.

List<String> bannedWords = Arrays.asList("darn", "golly", "gosh");

StringBuilder re = new StringBuilder();
for (String bannedWord : bannedWords)
{
    if (re.length() > 0)
        re.append("|");
    String quotedWord = Pattern.quote(bannedWord);
    re.append(quotedWord);
}

inputString = inputString.replaceAll(re.toString(), "[No cursing please!]");

How can it be modified to be case insensitive?

Upvotes: 0

Views: 205

Answers (3)

brc
brc

Reputation: 5391

You need to set the CASE_INSENSITIVE flag, or simply add (?i) to the beginning of your regex.

StringBuilder re = new StringBuilder("(?i)");

You'll also need to change your conditional to

if (re.length() > 4)

Setting the flag via @ratchetFreak's answer is probably best, however. It allows for your condition to stay the same (which is more intuitive) and gives you a clear idea of what's going on in the code.

For more info, see this question and in particular this answer which gives some decent explanation into using regex's in java.

Upvotes: 3

ratchet freak
ratchet freak

Reputation: 48196

use a precompiled java.util.regex.Pattern

Pattern p = Pattern.compile(re.toString(),Pattern.CASE_INSENSITIVE);//do this only once

inputString = p.matcher(inputString).replaceAll("[No cursing please!]");

Upvotes: 1

aioobe
aioobe

Reputation: 420991

Start the expression with (?i).

I.e., change re.toString() to "(?i)" + re.toString().

From the documentation of Pattern

(?idmsux-idmsux) Nothing, but turns match flags i d m s u x on - off

where i is the CASE_INSENSITIVE flag.

Upvotes: 3

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