Making regex case-insensitive

Question

I have created some lines of code for an email handler that will scrape my emails for a particular string (STA0123).

Code:

  // Find STA No. (in email body)
  Opportunity Opp = [SELECT id, STA_No__c Opportunity WHERE Id = :matcher.group(0)];
  String staNo = email.plainTextBody;
  Pattern staPattern = Pattern.compile('STA[0-9]{4}');
  Matcher matcherSta = staPattern.matcher(staNo);
  if (matcherSta.find())
    Opp.STA_No__c = matcherSta.group(0);

This works as expected but only with the first part of the string in capitals, STA0123 matches the pattern but sta0123 does not.

Answer 1

You need to use JAVA-like CASE_INSENSITIVE pattern (?i)

Something like this:

Pattern staPattern = Pattern.compile('(?i)STA[0-9]{4}');

Answer 2

To make it case insensitive, you can just modify your pattern as follows

   Pattern staPattern = Pattern.compile('[Ss][Tt][Aa][0-9]{4}');

This can be long winded if you have a long pattern, so then you use the ignore case modifier

 Pattern staPattern = Pattern.compile('(?i)sta[0-9]{4}');

Answer 3

Pattern.compile('[s|S]{1}[t|T]{1}[a|A]{1}[0-9]{4}'); should do the trick. Basically what this does is:

Find the letter "S" either lower or upper case (only 1), followed by the same rule for the letter "T" and "A", then followed by any digit (4 times).

I've tested this and it worked for all possible combinations:

STA1234
sTa1234
sta1234
...