package chap456;

import java.util.Scanner;
import java.util.TreeMap;

public class ToRoman {

	public static TreeMap<Integer, String> map = new TreeMap<Integer, String>();

	static {

		// put the value and key pairs in such a way that
		// every interger should be covered in roman number
		map.put(1000, "M");
		map.put(900, "CM");
		map.put(500, "D");
		map.put(400, "CD");
		map.put(100, "C");
		map.put(90, "XC");
		map.put(50, "L");
		map.put(40, "XL");
		map.put(10, "X");
		map.put(9, "IX");
		map.put(5, "V");
		map.put(4, "IV");
		map.put(1, "I");

	}

	public static String toRoman(int num) {
		
		// floorkey in treemap returns the greatest key less than or equal to the given key
		int value = map.floorKey(num);
		if (num == value) {
			return map.get(num);
		}
		return map.get(value) + toRoman(num - value);
	}

	public static void main(String[] args) {
		
		Scanner input = new Scanner(System.in);
		System.out.println("enter a number: ");
		int number= input.nextInt();
	    String romanNumber = ToRoman.toRoman(number);
		System.out.println("the respective roman number is: " +romanNumber);
		input.close();

	}

}

Output:

enter a number: 
96
the respective roman number is:XCVI