public static int binarySearch(List <String> sortedAL, String key, int lowIndex, int highIndex)
{
    int middle = (lowIndex + highIndex) / 2;

    if(highIndex < lowIndex)
    {
        //System.out.println(-1);
        return -1;
    }

    if(key.equalsIgnoreCase(sortedAL.get(middle)))
    {
        return middle;
    }

    /*
        str1.compareTo(str2)

        * if s1 > s2, it returns positive number
        * if s1 < s2, it returns negative number
        * if s1 == s2, it returns 0
     */

    else if(key.compareToIgnoreCase(sortedAL.get(middle)) < 0)
    {
        return binarySearch(sortedAL, key, lowIndex, middle - 1);
    }

    else
    {
        return binarySearch(sortedAL, key, middle + 1, highIndex);
    }
}