Java 实现大整数阶乘计算，并处理异常情况

import java.math.BigInteger;
import java.util.Scanner;

public class Factorial {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入一个整数：");
        String input = scanner.nextLine();

        try {
            BigInteger num = new BigInteger(input);
            BigInteger result = factorial(num);
            System.out.println(num + "! = " + result);
        } catch (NumberFormatException e) {
            try {
                int hexIndex = input.indexOf('x');
                if (hexIndex != -1) {
                    String hexStr = input.substring(hexIndex + 1);
                    BigInteger num = new BigInteger(hexStr, 16);
                    BigInteger result = factorial(num);
                    System.out.println(hexStr + "! = " + result);
                } else {
                    System.out.println("输入不是一个整数！");
                }
            } catch (NumberFormatException ex) {
                System.out.println("输入不是一个整数！");
            }
        }
    }

    public static BigInteger factorial(BigInteger n) {
        if (n.compareTo(BigInteger.ZERO) == 0 || n.compareTo(BigInteger.ONE) == 0) {
            return BigInteger.ONE;
        } else {
            return n.multiply(factorial(n.subtract(BigInteger.ONE)));
        }
    }
}