Regular Expression for UpperCase Letters In A String

Question

For the life of me, I can\'t figure out why this regular expression is not working. It should find upper case letters in the given string and give me the count. Any ideas are we

Answer 1

It doesn't work because you have 2 problems:

1. Regex is incorrect, it should be "[A-Z]" for ASCII letter or \p{Lu} for Unicode uppercase letters
2. You're not calling while (matcher.find()) before matcher.groupCount()

Correct code:

public void testCountTheNumberOfUpperCaseCharacters() {
    String testStr = "abcdefghijkTYYtyyQ";
    String regEx = "(\\p{Lu})";
    Pattern pattern = Pattern.compile(regEx);
    Matcher matcher = pattern.matcher(testStr);
    while (matcher.find())
        System.out.printf("Found %d, of capital letters in %s%n", 
          matcher.groupCount(), testStr);

}

UPDATE: Use this much simpler one-liner code to count number of Unicode upper case letters in a string:

int countuc = testStr.split("(?=\\p{Lu})").length - 1;