Integer to Letter Mapping

If you need to map an integer value to a letter value, for example: 0 = A, 1 = B, 2 = C, etc., you can follow this advice:

public static String getCharForNumber(int i){

    // return null for bad input
    if(i < 0){
        return null;
    }

    // convert to base 26
    String s = Integer.toString(i, 26);

    char[] characters = s.toCharArray();

    String result = "";
    for(char c : characters){
        // convert the base 26 character back to a base 10 integer
        int x = Integer.parseInt(Character.valueOf(c).toString(), 26);
        // append the ASCII value to the result
        result += String.valueOf((char)(x + 'A'));          
    }

    return result;
}

I generalized the algorithm to make use of base 26 conversion in order to deal with a list size greater than 26. It is worthwhile to note that the value BA, and not AA as some may expect, follows Z.