我已經檢查並測試過很多次了，實在找不出問題在哪裡。
所以我稍微改了一下我的程式，讓他自動產生測資跑個二十萬次看看，依然看不出問題在哪裡，實在沒辦法了，只好發問了。

錯誤訊息是這樣：
您的程式被監控系統中斷，可能是程式無法正常結束所導致。
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 14
	at A013.toRomanNumerals(A013.java:103) (改完是124行)
	at A013.main(A013.java:32) (改完是38行)

我的程式是這樣的：

package main;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Random;

public class A013 {
 /**
 * 由小到大排列的羅馬數字陣列
 * */
 private static final char[] RomanNumer = new char[] { 'I', 'V', 'X', 'L', 'C', 'D', 'M' };
 /**
 * 由小到大排列的阿拉伯數字陣列
 * */
 private static final int[] ArabicNumer = new int[] { 1, 5, 10, 50, 100, 500, 1000 };
 
 
 
 public static void main(String[] args) throws IOException {
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 String in;
 int count = 0;
 
// while (!(in = br.readLine()).equals("#")) {
 in = getTestString();
 while( count != 200000 ) {
 count++;
 String[] inArray = in.split(" ");
 int a = Integer.valueOf(inArray[0]);
 int b = Integer.valueOf(inArray[1]);
 System.out.println(inArray[0] + " - " + inArray[1] + " = " + (a-b));
 inArray[0] = toRomanNumerals(a);
 inArray[1] = toRomanNumerals(b);
 System.out.println(inArray[0] + " - " + inArray[1]);
// System.out.println(toArabicNumerals(inArray[0]) + " - " + toArabicNumerals(inArray[1]));
 
 int ans = toArabicNumerals(inArray[0]) - toArabicNumerals(inArray[1]);
 System.out.println(toRomanNumerals(ans));
 
 System.out.println(ans);
 if((a-b) != ans) {
 throw new RuntimeException();
 }
 in = getTestString();
 System.out.println("----------");
 }
 }
 
 /**
 * 隨機取得測試資料
 * */
 private static String getTestString() {
 int a = new Random().nextInt(3999)+1;
 int b = a==1 ? a: new Random().nextInt(a-1)+1;
 
 return String.format("%d %d", a,b);
 }
 /**
 * 查詢指定羅馬數字的索引位置
 * */
 private static int getNumerIndex(char romanNumer) {
 for (int i = 0; i < RomanNumer.length; i++) {
 if (RomanNumer[i] == romanNumer) {
 return i;
 }
 }
 throw new RuntimeException();
 }
 /**
 * 羅馬轉阿拉伯
 * */
 private static int toArabicNumerals(String inArray) {
 int total = 0;
 char[] inCArray = inArray.toCharArray();
 int[] inIArray = new int[inCArray.length];
 inIArray[0] = ArabicNumer[getNumerIndex(inCArray[0])];

 for (int i = 1; i < inCArray.length; i++) {
 if (((inCArray[i - 1] == 'I' || inCArray[i - 1] == 'X' || inCArray[i - 1] == 'C')
 && (getNumerIndex(inCArray[i - 1]) == (getNumerIndex(inCArray[i]) - 1)))
 || (inCArray[i] == 'M' && inCArray[i - 1] == 'C') || (inCArray[i] == 'C' && inCArray[i - 1] == 'X')
 || (inCArray[i] == 'X' && inCArray[i - 1] == 'I')) {
 inIArray[i - 1] = -inIArray[i - 1];
 inIArray[i] = ArabicNumer[getNumerIndex(inCArray[i])];
 } else {

 inIArray[i] = ArabicNumer[getNumerIndex(inCArray[i])];
 }
 }
 for (int x : inIArray) {
 total += x;
 }
 return total;
 }
 
 /**
 * 阿拉伯轉羅馬
 * */
 private static String toRomanNumerals(int input) {
 if (input == 0)
 return "ZERO";
 int digits = getNumLenght(input);
 int cinPutN = -1;
 char[] cinPut = new char[digits * 7];
 int digitMum = getDigitMum(input, digits);
 while (digits != 0) {
 if (digits != 4) {
 if (digitMum == 9) {
 cinPut[++cinPutN] = RomanNumer[getOdd(digits) - 1];
 cinPut[++cinPutN] = RomanNumer[getOdd(digits + 1) - 1];
 } else if (digitMum >= 5) {
 cinPut[++cinPutN] = RomanNumer[getEven(digits) - 1];
 digitMum -= 5;
 while (digitMum != 0) {
 cinPut[++cinPutN] = RomanNumer[getOdd(digits) - 1];
 digitMum--;
 }
 } else if (digitMum == 4) {
 cinPut[++cinPutN] = RomanNumer[getOdd(digits) - 1];
 cinPut[++cinPutN] = RomanNumer[getEven(digits) - 1];
 } else {
 while (digitMum != 0) {
 cinPut[++cinPutN] = RomanNumer[getOdd(digits) - 1];
 digitMum--;
 }
 }
 } else {
 while (digitMum != 0) {
 cinPut[++cinPutN] = 'M';
 digitMum--;
 }
 }

 digitMum = getDigitMum(input, --digits);
 }

 return new String(cinPut).trim();

 }
 
 
 /**
 * 取得指定順位的偶數
 * */
 private static int getEven(int order) {
 return 2 * order;
 }
 
 /**
 * 取得指定順位的奇數
 * */
 private static int getOdd(int order) {
 return 2 * order - 1;
 }
 
 /**
 * 取得數字長度
 * */
 private static int getNumLenght(int num) {
 num = num > 0 ? num : -num;
 if (num == 0) {
 return 1;
 }
 return (int) Math.log10(num) + 1;
 }
 
 /**
 * 取得指定位數的數字
 * */
 private static int getDigitMum(int number, int position) {
 return (int) (number / Math.pow(10, position - 1)) % 10;
 }
}