java - 将数值转换为罗马数字

Question

我需要使用不同的方法将数值转换为罗马数字值。下面是我已经创建的代码。

public static void main (String[]args){
    Scanner in = new Scanner(System.in);
    int input = in.nextInt();
    String s = "";
}
private static int promptUserForNumber(Scanner inScanner) {
    System.out.print ("Enter a number between 1 and 3999 (0 to quit): ");
    int input = inScanner.nextInt();
    if((input < 1 && input > 3999) && input != 0){
        System.out.println("Error, number must be between 1 and 3999");
         if (input == 0){
            System.out.println("Goodbye");
         }  
        }
    return input;
}
public static String convertNumberToNumeral(int input) {    
    String s = "";
    Scanner in = new Scanner(System.in);
    while (input >= 1000){
        s += "M";
        input -= 1000;
    }
    while (input >= 900){
        s += "CM";
        input -= 900;
    }
    while (input >= 500){
        s += "D";
        input -= 500;
    }
    while (input >= 400){
        s += "CD";
        input -= 400;
    while (input >= 100){
        s += "C";
        input -= 100;
    }
    while (input >= 90){
        s += "XC";
        input -= 90;
    }
    while (input >= 50){
        s += "L";
        input -= 50;
    }
    while (input >= 40){
        s += "XL";
        input -= 40;
    }
    while (input >= 10){
        s += "X";
        input -= 10;
    }
    while (input >= 9){
        s += "IX";
        input -= 10;
    }
    while (input >= 5){
        s += "V";
        input -= 5;
    }
    while (input >= 4){
        s += "IV";
        input -= 4;
        }
    while (input >= 1){
        s += "I";
        input -= 1;
    }
    }
    return s;
}

到目前为止，有一个无限循环，我不知道哪里出了问题。输出应该是输入 0 到 3999 之间的数值，然后在下一行输出罗马数字。谢谢!

Answer 1

    while (input >= 400){
    s += "CD";
    input -= 400;

}这里还需要一个“}”