将罗马数字转换为 Java 中的整数

Question

我的导师给我一个挑战，让用户输入一个数字或罗马数字，然后让程序将其转换为其他数字。我已经让它能够将整数转换为罗马数字，但我不知道如何反过来做。我曾尝试寻求帮助，但对我的情况没有任何帮助。你们中的一些人可能给了我链接或说这是重复的，但是，我知道如何进行转换（是的，我做了一个 HUGE 这个问题的错误）。我的问题是能够同时做这两件事。我不知道怎么让它像：哦，你输入了一个整数，把它转换成罗马数字，让它也像：哦，罗马数字时间！将其转换为整数。 请帮忙！！

import java.util.Scanner;

public class DecimalRoman {
@SuppressWarnings("resource")
public static void main(String args[]) {
    System.out.print("Enter a Number: ");
    Decimal2Roman();
}

public static void Decimal2Roman() {
    Scanner scan = new Scanner(System.in);
    int num = scan.nextInt();
    if(num>0 && num<4000) //checking whether the number entered is within the range [1-3999]
    {

        /*Saving the Roman equivalent of the thousand, hundred, ten and units place of a decimal number*/
        String thou[]={"","M","MM","MMM"};
        String hund[]={"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"};
        String ten[]={"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"};
        String unit[]={"","I","II","III","IV","V","VI","VII","VIII","IX"};

        /*Finding the digits in the thousand, hundred, ten and units place*/
        int th=num/1000;
        int h=(num/100)%10;
        int t=(num/10)%10;
        int u=num%10;

        /*Displaying equivalent roman number*/
        System.out.println("The Roman Numeral of " + num + " is " + thou[th]+hund[h]+ten[t]+unit[u]);
    }

    /*Displaying an error message if the number entered is out of range*/
    else
        System.out.println("\nYou entered a number out of Range.\nPlease enter a number in the range [1-3999]");
}
}

Answer 1

根据您上次的编辑，要识别您获得的输入类型，您可以使用 Scanner.hasNextInt() 方法：

Scanner scan = new Scanner(System.in);
if (scan.hasNextInt()) {
    int arabicNumber = scan.nextInt();
} else {
    String romanNumber = scan.next();
}

Answer 2

您必须创建一个基本值索引并将其与数值相匹配。一个小例子：

I = 1
V = 5
X = 10

而且你必须看到位置 left/right 才能求和和减去。这是逻辑，代码由您决定。

将罗马数字转换为 Java 中的整数

Converting Roman Numerals to Integers in Java

java

integer

roman-numerals