int prevIoUsCharValue = 0;
int total = 0;

for (int i = 0; i < input.length(); i++) {
    char current = input.charAt(i);

    RomanNumeral romanNum = RomanNumeral.valueOf(Character.toString(current));

    if (prevIoUsCharValue > 0) { 
        total += (romanNum.getNumericValue() - prevIoUsCharValue);
        prevIoUsCharValue = 0;
    } else {
        if (i < input.length() - 1) {

            char next = input.charAt(i + 1);
            RomanNumeral nextNum = RomanNumeral.valueOf(Character.toString(next));
            if (romanNum.getNumericValue() < nextNum.getNumericValue()) {
                prevIoUsCharValue = romanNum.getNumericValue();
            }
        }
        if (prevIoUsCharValue == 0) {
            total += romanNum.getNumericValue();
        }

    }

}