RomanToDecimal.java

public class RomanToDecimal{
   public static void romanToDecimal(String romanNumber){
       int decimal = 0;
       int lastNumber = 0;
       String romanNumeral = romanNumber.toUpperCase();
       for (int x = romanNumeral.length() - 1; x >= 0 ; x--){
           char convertToDecimal = romanNumeral.charAt(x);
           switch (convertToDecimal){
               case 'M':
                   decimal = processDecimal(1000, lastNumber, decimal);
                   lastNumber = 1000;
                   break;
               case 'D':
                   decimal = processDecimal(500, lastNumber, decimal);
                   lastNumber = 500;
                   break;
               case 'C':
                   decimal = processDecimal(100, lastNumber, decimal);
                   lastNumber = 100;
                   break;
               case 'L':
                   decimal = processDecimal(50, lastNumber, decimal);
                   lastNumber = 50;
                   break;
               case 'X':
                   decimal = processDecimal(10, lastNumber, decimal);
                   lastNumber = 10;
                   break;
               case 'V':
                   decimal = processDecimal(5, lastNumber, decimal);
                   lastNumber = 5;
                   break;
               case 'I':
                   decimal = processDecimal(1, lastNumber, decimal);
                   lastNumber = 1;
                   break;
           }
       }
       System.out.println("Decimal number : "+decimal);
   }
   
   public static int processDecimal(int decimal, int lastNumber, int lastDecimal){
       if (lastNumber > decimal)
           return lastDecimal - decimal;
       else
           return lastDecimal + decimal;
   }
   
   public static void main(java.lang.String args[]){
      String roman = "VI";
      romanToDecimal(roman);
   }
}