Regex in Java: match groups until first symbol occurrence

Question

My string looks like this:

"Chitkara DK, Rawat DJY, Talley N. The epidemiology of childhood recurrent abdominal pain in Western countries: a systematic review. Am J Gastroenterol. 2005;100(8):1868-75. DOI."

What I want is to get letters in uppercase (as separate words only) until first dot, to get: DK DJY N. But not other characters after, like J DOI.

Here`s my part of code for Java class Pattern:

\\b[A-Z]{1,3}\\b

Is there a general option in regex to stop matching after certain character?

Answer 1

You can make use of the contionous matching using \G and extract your desired matches from the first capturing group:

(?:\\G|^)[^.]+?\\b([A-Z]{1,3})\\b

You need to use the MULTILINE flag to use this in a multiline context. If your content is always a single line you may drop the |^ from your pattern.

See https://regex101.com/r/JXIu21/3

Note that regex101 uses a PCRE pattern, but all features used are also available in Java regex.

Answer 2

Sebastian Proske's answer is great, but it's often easier (and more readable) to split complex parsing tasks into separate steps. We can split your goal into two separate steps and thereby create a much simpler and more clearly-correct solution, using your original pattern.

private static final Pattern UPPER_CASE_ABBV_PATTERN = Pattern.compile("\\b[A-Z]{1,3}\\b");

public static List<String> getAbbreviationsInFirstSentence(String input) {
  // isolate the first sentence, since that's all we care about
  String firstSentence = input.split("\\.")[0];
  // then look for matches in the first sentence
  Matcher m = UPPER_CASE_ABBV_PATTERN.matcher(firstSentence);
  List<String> results = new ArrayList<>();
  while (m.find()) {
    results.add(m.group());
  }
  return results;
}