Roman Numerals. Could you point out my mistakes further down the road?

Question

Beginner here. This piece of code converts number into roman numerals in multiples of 50 if not 10 if not 9 and down to 0. Methods are so intertwined. Is there something (just at a glance) you could suggest I should avoid doing? Thank You.

 public static void main(String[] args) {

     System.out.println(fiftyAndAbove(37));

 }

 public static String nineAndDown(int number) {
     String  one = "I", five = "V", ten = "X", sum = "";
     if(number == 5) {
         return five;
     } else if(number == 9) {
         return one + ten;
     }

     else if(number > 5) {
         for(int i=1; i<=number-5; i++) {
             sum += one;
         }
         return five + sum;
     } else {
         if(number == 4 ) {
             return one + five;
         } else
             for(int i=1; i <=number; i++) {
                 sum += one;
             }
     } return sum;
 }

 public static String tenAndAbove(int number) {
     int remainder = number % 10, numberOftens = number/10;
     String ten = "X", sum = "";
     if(numberOftens > 0) {
         while(numberOftens > 0) {
             sum += ten;
             numberOftens -= 1;
         }
     }
     return sum + nineAndDown(remainder);
 }

 public static String fiftyAndAbove(int number) {
     int remainder = number % 50, numberOfFifty = number/50;
    String fifty = "L", sum = "";
     if(numberOfFifty > 0) {
         while(numberOfFifty > 0) {
             sum += fifty;
             numberOfFifty -= 1;
         }
     }
     return sum + tenAndAbove(remainder);
 }

Which Java version(s) do you wish to work with? – Armali Oct 23 '19 at 13:49 — Armali, Oct 23 '19 at 13:49

Armali · Answer 1 · 2019-10-23T15:21:05.787

Is there something (just at a glance) you could suggest I should avoid doing?

I'd not unnecessarily complicate the logic as with

     if(numberOfFifty > 0) {
         while(numberOfFifty > 0) {
             …
         }
     }

which is equivalent to

     while (numberOfFifty > 0)
     {
         …
     }

You could also have a look at this implementation and see what you prefer:

import java.util.Arrays;
…
 public static String fiftyAndAbove(int number)
 {
     int remainder = number%50, numberOfFifty = number/50;
     char [] Ls = new char [numberOfFifty];
     Arrays.fill(Ls, 'L');
     return new String(Ls) + tenAndAbove(remainder);
 }

You have four places like this in your program where you need a string of a character repeated. If you're willing to require a certain Java version or above, you can also use one of the methods described at Java: String - add character n-times; otherwise I'd suggest to use a function to do it.

You could also think about whether you find

     String  one = "I", five = "V", ten = "X", sum = "";
     if(number == 5) {
         return five;
     } else if(number == 9) {
         return one + ten;
     }

really better than

     if (number == 5) return "V";
     if (number == 9) return "IX";

Roman Numerals. Could you point out my mistakes further down the road?

1 Answers1