jodd.format.RomanNumber Maven / Gradle / Ivy
// Copyright (c) 2003-2011, Jodd Team (jodd.org). All Rights Reserved.
package jodd.format;
/**
* Works with roman numbers.
*/
public class RomanNumber {
public static final int[] VALUES = new int[] {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};
public static final String[] LETTERS = new String[] {"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};
/**
* Converts to roman number.
*/
public static String romanize(int value) {
StringBuilder roman = new StringBuilder();
int n = value;
for (int i = 0; i < LETTERS.length; i++) {
while (n >= VALUES[i]) {
roman.append(LETTERS[i]);
n -= VALUES[i];
}
}
return roman.toString();
}
/**
* Converts to arab numbers.
*/
public static int numberize(String roman) {
int start = 0, value = 0;
for (int i = 0; i < LETTERS.length; i++) {
while (roman.startsWith(LETTERS[i], start)) {
value += VALUES[i];
start += LETTERS[i].length();
}
}
return start == roman.length() ? value : -1;
}
/**
* Checks if some string is valid roman number.
*/
public static boolean isRoman(String roman) {
return roman.equals(romanize(numberize(roman)));
}
}