I am going to use the regular expression to catch the word with repeated characters (letter, digit, or underscore).
I found pretty interesting results during my testing. If I am using apex code, Matcher.matches() would not catch it, while Matcher.find() would return correct value. If I am trying the REGEX() in the formula field, it never works out. The pattern I am using is '(\w)\1+'. Just wonder how to get REGEX() worked for this requirement.

//Pasted the Apex code for the reference. String stringToMatch = 'abcccdefg'; // String stringToMatch = 'abcdefg'; Pattern p = Pattern.compile('(\w)\1+'); Matcher m = p.matcher(stringToMatch); system.debug(m.find()); System.debug(m.matches()); if (m.find()) { system.debug('Duplicate character ' + m.group(1)); }

Any help would be truly appreciated. Thank you very much in advance.

Regards, Rong