Java Convert Integer Number to Roman Number



In this source code example, we will write a Java program to convert an integer number to Roman number.
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Java Convert Integer Number to Roman Number

Here is a Java program to convert integer number to Roman number:
package net.sourcecodeexamples.java.Conversions;

import java.util.Scanner;

/**
 * Converting Integers into Roman Numerals
 *
 *('I', 1);
 *('IV',4);
 *('V', 5);
 *('IV',9);
 *('X', 10);
 *('XL',40;
 *('L', 50);
 *('XC',90);
 *('C', 100);
 *('D', 500);
 *('M', 1000);
 *
 */


public class IntegerToRoman {
    private static int[] allArabianRomanNumbers = new int[] {
        1000,
        900,
        500,
        400,
        100,
        90,
        50,
        40,
        10,
        9,
        5,
        4,
        1
    };
    private static String[] allRomanNumbers = new String[] {
        "M",
        "CM",
        "D",
        "CD",
        "C",
        "XC",
        "L",
        "XL",
        "X",
        "IX",
        "V",
        "IV",
        "I"
    };

    //Value must be > 0

    public static String integerToRoman(int num) {
        if (num <= 0) {
            return "";
        }

        StringBuilder builder = new StringBuilder();

        for (int a = 0; a < allArabianRomanNumbers.length; a++) {
            int times = num / allArabianRomanNumbers[a];
            for (int b = 0; b < times; b++) {
                builder.append(allRomanNumbers[a]);
            }
            num -= times * allArabianRomanNumbers[a];
        }

        return builder.toString();
    }

    public static void main(String[] args) {

        System.out.print("Enter the integer number : ");
        try (Scanner scanner = new Scanner(System.in)) {
            int number = scanner.nextInt();
            String output = IntegerToRoman.integerToRoman(number);
            System.out.println("Roman number : " + output);
        }
    }
}

Output

Enter the integer number : 5
Roman number : V

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