JavaExercism/exercises/acronym/.meta/src/reference/java/Acronym.java

import java.util.regex.Matcher;
import java.util.regex.Pattern;

final class Acronym {

    private final String acronym;

    Acronym(String phrase) {
        acronym = generateAcronym(phrase);
    }

    String get() {
        return acronym;
    }

    private String generateAcronym(String phrase){
        final Pattern BREAK_WORDS = Pattern.compile("[A-Z]+[a-z]*|[a-z]+");
        final Matcher matcher = BREAK_WORDS.matcher(phrase);
        final StringBuilder b = new StringBuilder();
        while (matcher.find()){
            b.append(matcher.group().charAt(0));
        }
        return b.toString().toUpperCase();
    }

}