I'm very new with java, I haven't learned arrays and maps yet, so I have to create a program to convert from integer to Roman and vice-versa. My conversion from int to string works, but not string to int. It somehow does an infinite loop and I'm not too sure why. What could I change to my while loop to make it stop its infinite process ? We don't have to consider XI and such, so 4 = IIII 9 = VIIII We only take into account M, D, C, L, X, V, I We needed to create 3 constructors, one empty, one that takes a string, and one that takes a int My server class :

package jfauvelle_G10_A04;

public class RomanNumeral {
    private String romanNum = "";
    private int decimalNum = 0;

    public RomanNumeral() {
        romanNum = "";
        decimalNum = 0;
    }

    public RomanNumeral(String r) {
        decimalNum = convertRomanToInteger(r);
        romanNum = r;
    }

    public RomanNumeral(int i) {
        romanNum = convertIntegerToRoman(i);
        decimalNum = i;
        
    }

    public void setRomanNumeral(String r) {
        romanNum = r;
    }

    public String getRomanNumeral() {
        return romanNum;
    }

    public void setDecimalNumeral(int i) {
        decimalNum = i;
    }

    public int getDecimalNumeral() {
        return decimalNum;

    }

    public String convertIntegerToRoman(int r) {
        int roman = r; 
        String finalRoman = "";

        while (roman >= 1000) {
            finalRoman = finalRoman   "M";
            roman -= 1000;
        } // while(r >= 1000)

        while (roman >= 500) {
            finalRoman = finalRoman   "D";
            roman -= 500;

        } // while(r >= 500)

        while (roman >= 100) {
            finalRoman = finalRoman   "C";
            roman -= 100;
        } // while(r >= 100)

        while (roman >= 50) {
            finalRoman = finalRoman   "L";
            roman -= 50;
        } // while(r >= 50)

        while (roman >= 10) {
            finalRoman = finalRoman   "X";
            roman -= 10;

        } // while(r >= 10)

        while (roman >= 5) {
            finalRoman = finalRoman   "V";
            roman -= 5;
        } // while(r >= 5)

        while (roman >= 1) {
            finalRoman = finalRoman   "I";
            roman -= 1;
        } 

        return finalRoman;
    }

    private int convertRomanToInteger(String n) {
        String decimal = n;
        int finalDecimal = 0;
          
        
        for (int i = 0; i <= decimal.length(); i  ) {
            while (decimal.charAt(i) == 'M') {
                finalDecimal  = 1000;
            } // while(n.charAt(i) == 'M')
        
            while (decimal.charAt(i) == 'D') {
                finalDecimal  = 500;
            } // while(n.charAt(i) == 'D')
            
            while (decimal.charAt(i) == 'C') {
                finalDecimal  = 100;
            } // while(n.charAt(i) == 'C')
            

            while (decimal.charAt(i) == 'L') {
                finalDecimal  = 50;
            } // while(n.charAt(i) == 'L')
            

            while (decimal.charAt(i) == 'X') {
                finalDecimal  = 10;
            } // while(n.charAt(i) == 'X')
            

            while (decimal.charAt(i) == 'V') {
                finalDecimal  = 5;
            } // while(n.charAt(i) == 'V')
            

            while (decimal.charAt(i) == 'I') {
                finalDecimal  = 1;
            } // while(n.charAt(i) == 'I')
            
        } // for
        return finalDecimal;

    }// convertRomanToInteger()
}

Main class:

public class RomanNumeralCalculatorTestCase {

    public static void main(String[] args) {
        boolean working = true;
        RomanNumeral case1 = new RomanNumeral();
        case1.setRomanNumeral("XVI");
        if (case1.getRomanNumeral() != "XVI") {
            working = false;
            System.err.println("ERROR: Roman numeral was not set properly. It is "   case1.getRomanNumeral()
                      ". It should be XVI");
        }//if
        case1.setDecimalNumeral(2004);
        if (case1.getDecimalNumeral() != 2004) {
            working = false;
            System.err.println("ERROR: Decimal number was not set properly. It is "   case1.getDecimalNumeral()
                      ". It should be XVI");
        }

        RomanNumeral case2 = new RomanNumeral(1000);
        String s = "M";
        if(!(case2.getRomanNumeral().equals(s))) {
            working = false;
            System.err.println("ERROR: Decimal number was not set properly. It is "   case2.getRomanNumeral()
                      ", it should be M.");
        }
        RomanNumeral case3 = new RomanNumeral("M");
        if(case3.getDecimalNumeral() != 1000) {
            working = false;
            System.err.println("ERROR: Decimal number was not set properly. It is "   case3.getDecimalNumeral()
                      ". It should be 1000");
        }
        if(working)
            System.out.print("Congratz ! The test case work !");
    }// public static void main(String[] args)
}// public class RomanNumeralCalculatorTestCase

I tried to use a small and simple array, but it remained as a string. If someone has a suggestion of a small and very simple array that I can understand, I would be really open to that solution. I just want to understand the solution.

CodePudding user response：

you probably have to change the decimalNumeral aswell when calling setRomanNumeral and vice versa otherwise the values never change

so something like

public void setDecimalNumeral(int i) {
        decimalNum = i;
        romanNum = convertIntegerToRoman(i);
    }

also inside your while loop you never change the condition, so if you get in, you never get out, so you probably should change them to if statements

 for (int i = 0; i <= decimal.length(); i  ) {
        if (decimal.charAt(i) == 'M') {
            finalDecimal  = 1000;
        } // if(n.charAt(i) == 'M')