Java Convert Roman to Integer Number

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

Here is a Java program to convert Roman number to an integer number:
package net.sourcecodeexamples.java.Conversions; import java.util.*; public class RomanToInteger { private static Map < Character, Integer > map = new HashMap < Character, Integer > () { private static final long serialVersionUID = 87605733047260530 L; { put('I', 1); put('V', 5); put('X', 10); put('L', 50); put('C', 100); put('D', 500); put('M', 1000); } }; /**  * This function convert Roman number into Integer  *  * @param A Roman number string  * @return integer  */ public static int romanToInt(String A) { char prev = ' '; int sum = 0; int newPrev = 0; for (int i = A.length() - 1; i >= 0; i--) { char c = A.charAt(i); if (prev != ' ') { // checking current Number greater then previous or not newPrev = map.get(prev) > newPrev ? map.get(prev) : newPrev; } int currentNum = map.get(c); // if current number greater then prev max previous then add if (currentNum >= newPrev) { sum += currentNum; } else { // subtract upcoming number until upcoming number not greater then prev max sum -= currentNum; } prev = c; } return sum; } public static void main(String[] args) { try (Scanner input = new Scanner(System.in)) { System.out.print("Enter the Roman number : "); String number = input.next(); int sum = romanToInt(number); System.out.print("Integer number : "); System.out.println(sum); } } }

Output

Enter the Roman number : DCCVII Integer number : 707
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