public static String asAlphaNumeric(int i) {
        StringBuilder stringBuilder = new StringBuilder();
        int index = i % MAX;
        int ratio = i / MAX;

        if (index == 0) {
            ratio--;
            index = MAX;
        }

        for (int j = 0; j <= ratio; j++) {
            stringBuilder.append(ALPHABET[index - 1]);
        }
        return stringBuilder.toString();
    }
@Test
    public void testAlphaUpper() {
        assertEquals("A", AutoPageNumberUtils.asAlphaNumeric(1));
        assertEquals("Z", AutoPageNumberUtils.asAlphaNumeric(26));
        assertEquals("AA", AutoPageNumberUtils.asAlphaNumeric(27));
        assertEquals("ZZ", AutoPageNumberUtils.asAlphaNumeric(52));
        assertEquals("AAA", AutoPageNumberUtils.asAlphaNumeric(53));
        assertEquals("ZZZ", AutoPageNumberUtils.asAlphaNumeric(78));
    }