Roman to Integer

RomanToInteger.java

import java.util.Map;

public class RomanToInteger {
    private static final Map<Character, Integer> symbols =
            Map.of('I', 1, 'V', 5, 'X', 10, 'L', 50, 'C', 100, 'D', 500, 'M', 1000);

    public int convert(String romanNumeral) {
        int result = 0;
        for (int i = 0; i < romanNumeral.length(); i++) {
            char currentChar = romanNumeral.charAt(i);
            boolean isLastNumeral = i == romanNumeral.length() - 1;
            if (isLastNumeral) {
                return result + symbols.get(currentChar);
            }
            if (compare(currentChar, romanNumeral.charAt(i + 1)) < 0) {
                int subtraction = convertSubtraction(currentChar, romanNumeral.charAt(i + 1));
                result += subtraction;
                i++;
            } else {
                result += symbols.get(currentChar);
            }
        }
        return result;
    }

    private int compare(char a, char b) {
        return Integer.compare(symbols.get(a), symbols.get(b));
    }

    private int convertSubtraction(char a, char b) {
        return symbols.get(b) - symbols.get(a);
    }
}