java - 罗马数字到阿拉伯数字的转换器

Question

您好，我正在尝试编写将罗马数字(如 MCLII)转换为阿拉伯数字的程序。在电脑和教科书前度过几个小时后，我有一个未完成的代码。请帮我找出为什么程序出错并且最后不打印任何内容。谢谢

public class Main {
public static void romanToDecimal(java.lang.String romanNumber) {
int decimal = 0;
int lastNumber = 0;
String romanNumeral = romanNumber.toUpperCase();

for (int x = romanNumeral.length() - 1; x >= 0 ; x--)
{
    char convertToDecimal = romanNumeral.charAt(x);

    switch (convertToDecimal)
    {
        case 'M':
            decimal = processDecimal(1000, lastNumber, decimal);
            lastNumber = 1000;
            break;

        case 'D':
            decimal = processDecimal(500, lastNumber, decimal);
            lastNumber = 500;
            break;

        case 'C':
            decimal = processDecimal(100, lastNumber, decimal);
            lastNumber = 100;
            break;

        case 'L':
            decimal = processDecimal(50, lastNumber, decimal);
            lastNumber = 50;
            break;

        case 'X':
            decimal = processDecimal(10, lastNumber, decimal);
            lastNumber = 10;
            break;

        case 'V':
            decimal = processDecimal(5, lastNumber, decimal);
            lastNumber = 5;
            break;

        case 'I':
            decimal = processDecimal(1, lastNumber, decimal);
            lastNumber = 1;
            break;
    }
 }
 System.out.println(decimal);
 }

 public static int processDecimal(int decimal, int lastNumber, int lastDecimal)
 {
 if (lastNumber > decimal)
 {
    return lastDecimal - decimal;
 } else {
    return lastDecimal + decimal;
 }
 }

 public static void main(java.lang.String args[]) {
 System.out.println("PLEASE ENTER ANY NUMBER IN ROMAN NUMERIC FORMAT:");
 Scanner input = new Scanner(System.in);
 int romanToDecimal;
 romanToDecimal = input.nextInt();
 }
 }

Answer 1

您没有调用任何方法，因此它不会执行任何操作。只会打印此内容

 System.out.println("PLEASE ENTER ANY NUMBER IN ROMAN NUMERIC FORMAT:");

调用如下方法

romanToDecimal("some tring");

因此您正在从控制台获取用户的输入

就这样吧

 Scanner input = new Scanner(System.in);
romanToDecimal(input);