Convert letters into numbers

Question

I need to write a method that converts letters from a word into a number according to the telephone buttons.
I figured I was at a good start by putting the string of the word into a character array, but how would I assign each of those letters to its corresponding number?
Thanks in advance.

Answer 1

changes to code that fills the hashmap. more concise (less interpretable)
import java.util.HashMap;
import java.util.Map;
class HashMapTester2
    private Map<Character, Integer> phoneHash;
    // constructor
    // for converting alphabetical characters to numbers based on the
    // phone dialing pad.
    public HashMapTester2()
        phoneHash = new HashMap<Character, Integer>();
        fillMap();
    private void fillMap()
        for (char myChar = 'a'; myChar <= 'z'; myChar++)
            int distanceFrom_a = (int)(myChar - 'a');
            if (myChar > 'r') // 's' hangs back w/ the pqr group.
                distanceFrom_a -= 1;
            if (myChar > 'y')  // 'z' hangs back w/ the wyz group.
                distanceFrom_a -= 1;
            // 2 is due to the numbers starting at 2
            // 3 is due to the letters being grouped in 3's, all sharing
            // the same number.
            int number = (int)(2 + (distanceFrom_a) / 3);
            phoneHash.put(myChar, number);  // insert reg char
            // insert uppercase version, same number
            phoneHash.put(Character.toUpperCase(myChar), number);
    // convert string to a long number based on results of
    // the string's characters run through the hashmap
    public long convertStr(String s) throws IndexOutOfBoundsException
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < s.length(); i++)
            char myChar = s.charAt(i);
            if ((myChar >= 'a' && myChar <= 'z') || (myChar >= 'A' && myChar <= 'Z'))
                sb.append(phoneHash.get(myChar));   
            else
                throw new IndexOutOfBoundsException();
        return Long.valueOf(sb.toString());
    public static void main(String[] args)
        HashMapTester2 hmt = new HashMapTester2();
        System.out.println(hmt.convertStr("aaa"));
        System.out.println(hmt.convertStr("What"));
        System.out.println(hmt.convertStr("the"));
        System.out.println(hmt.convertStr("heck"));
        System.out.println(hmt.convertStr("Fubar"));
        System.out.println(hmt.convertStr("Snafu"));
        System.out.println(hmt.convertStr("abcdefghijklm"));
        System.out.println(hmt.convertStr("nopqrstuvwxyz"));
        System.out.println();
        System.out.println(hmt.convertStr("abc"));
        System.out.println(hmt.convertStr("def"));
        System.out.println(hmt.convertStr("ghi"));
        System.out.println(hmt.convertStr("jkl"));
        System.out.println(hmt.convertStr("mno"));
        System.out.println(hmt.convertStr("pqrs"));
        System.out.println(hmt.convertStr("tuv"));
        System.out.println(hmt.convertStr("wxyz"));
}