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java - 超过金额限制后不显示消息

问题描述

当我输入超过 3999 的数字时，该消息未显示

我试图在方法内移动消息，但这只会导致更多错误。

import java.util.Scanner;

public class RomanNumerals {

    public static String convert(int n) {
String roman = "";
if ((n >= 0) && (n <= 3999)) {
    int thousand = (n / 1000);
    int hundred = (n % 1000) / 100;
    int tens = (n % 100) / 10;
    int units = (n % 10);

    if (thousand >= 1) {
        if (thousand == 1)
            roman += "M";
        else if (thousand == 2)
            roman += "MM";
        else roman += "MMM";
    }

    if (hundred >= 0) {
        if (hundred == 0)
            roman += "";
        else if (hundred == 1)
            roman += "C";
        else if (hundred == 2)
            roman += "CC";
        else if (hundred == 3)
            roman += "CCC";
        else if (hundred == 4)
            roman += "CD";
        else if (hundred == 5)
            roman += "D";
        else if (hundred == 6)
            roman += "DC";
        else if (hundred == 7)
            roman += "DCC";
        else if (hundred == 8)
            roman += "DCCC";
        else
            roman += "CM";
    }

    if (tens >= 0) {
        if (tens == 0)
            roman += "";
        else if (tens == 1)
            roman += "X";
        else if (tens == 2)
            roman += "XX";
        else if (tens == 3)
            roman += "XXX";
        else if (tens == 4)
            roman += "XL";
        else if (tens == 5)
            roman += "L";
        else if (tens == 6)
            roman += "LX";
        else if (tens == 7)
            roman += "LXX";
        else if (tens == 8)
            roman += "LXXX";
        else
            roman += "XC";
    }

    if (units >= 0) {
        if (units == 0)
            roman += "";
        else if (units == 1)
            roman += "I";
        else if (units == 2)
            roman += "II";
        else if (units == 3)
            roman += "III";
        else if (units == 4)
            roman += "IV";
        else if (units == 5)
            roman += "V";
        else if (units == 6)
            roman += "VI";
        else if (units == 7)
            roman += "VII";
        else if (units == 8)
            roman += "VIII";
        else
            roman += "IX";
    }
} else {
    roman = "Number cannot be converted as it exceeds over 3999";
}
return roman;

}

我希望用户输入超过 3999 后的输出显示消息“无法转换数字，因为它超过了 3999”但是当我写一个超过 3999 的数字时，程序就会停止。其他一切正常，并以罗马数字显示正确的整数

有人可以帮我解决这个问题，因为我很困惑

标签： java

解决方案

经典案例，说明您如何因为缩进不佳而错过看到问题。

以下else是 withif (units >= 0)而不是 with if ((n >= 0) && (n <= 3999))：

} else {
    roman = "Number cannot be converted as it exceeds over 3999";
}

此外，在不相关的注释中，您的条件if (units >= 0)始终为真，因此您可能希望删除此检查或更改它。

编辑convert：修复右大括号后的完整方法：

public static String convert(int n) {
    String roman = "";
    if ((n >= 0) && (n <= 3999)) {
        int thousand = (n / 1000);
        int hundred = (n % 1000) / 100;
        int tens = (n % 100) / 10;
        int units = (n % 10);

        if (thousand >= 1) {
            if (thousand == 1)
                roman += "M";
            else if (thousand == 2)
                roman += "MM";
            else roman += "MMM";
        }

        if (hundred >= 0) {
            if (hundred == 0)
                roman += "";
            else if (hundred == 1)
                roman += "C";
            else if (hundred == 2)
                roman += "CC";
            else if (hundred == 3)
                roman += "CCC";
            else if (hundred == 4)
                roman += "CD";
            else if (hundred == 5)
                roman += "D";
            else if (hundred == 6)
                roman += "DC";
            else if (hundred == 7)
                roman += "DCC";
            else if (hundred == 8)
                roman += "DCCC";
            else
                roman += "CM";
        }

        if (tens >= 0) {
            if (tens == 0)
                roman += "";
            else if (tens == 1)
                roman += "X";
            else if (tens == 2)
                roman += "XX";
            else if (tens == 3)
                roman += "XXX";
            else if (tens == 4)
                roman += "XL";
            else if (tens == 5)
                roman += "L";
            else if (tens == 6)
                roman += "LX";
            else if (tens == 7)
                roman += "LXX";
            else if (tens == 8)
                roman += "LXXX";
            else
                roman += "XC";
        }

        if (units >= 0) {
            if (units == 0)
                roman += "";
            else if (units == 1)
                roman += "I";
            else if (units == 2)
                roman += "II";
            else if (units == 3)
                roman += "III";
            else if (units == 4)
                roman += "IV";
            else if (units == 5)
                roman += "V";
            else if (units == 6)
                roman += "VI";
            else if (units == 7)
                roman += "VII";
            else if (units == 8)
                roman += "VIII";
            else
                roman += "IX";
        }
    } else {
        roman = "Number cannot be converted as it exceeds over 3999";
    }
    return roman;
}

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