一段对16进制字符串进行异或的代码。

public String xorHex(String a, String b) {        char[] chars = new char[a.length()];        for (int i = 0; i < chars.length; i++) {            chars[i] = toHex(fromHex(a.charAt(i)) ^ fromHex(b.charAt(i)));        }        return new String(chars);    }    private static int fromHex(char c) {        if (c >= '0' && c <= '9') {            return c - '0';        }        if (c >= 'A' && c <= 'F') {            return c - 'A' + 10;        }        if (c >= 'a' && c <= 'f') {            return c - 'a' + 10;        }        throw new IllegalArgumentException();    }    private char toHex(int nybble) {        if (nybble < 0 || nybble > 15) {            throw new IllegalArgumentException();        }        return "0123456789ABCDEF".charAt(nybble);    }