Java tutorial
//package com.java2s; public class Main { public static String convertMaskedPhone(String phone) { StringBuilder phoneNumber = new StringBuilder(phone); for (int i = 0; i < phoneNumber.length(); i++) { switch (Character.toLowerCase(phoneNumber.charAt(i))) { case 'a': case 'b': case 'c': phoneNumber.setCharAt(i, '2'); break; case 'd': case 'e': case 'f': phoneNumber.setCharAt(i, '3'); break; case 'g': case 'h': case 'i': phoneNumber.setCharAt(i, '4'); break; case 'j': case 'k': case 'l': phoneNumber.setCharAt(i, '5'); break; case 'm': case 'n': case 'o': phoneNumber.setCharAt(i, '6'); break; case 'p': case 'q': case 'r': case 's': phoneNumber.setCharAt(i, '7'); break; case 't': case 'u': case 'v': phoneNumber.setCharAt(i, '8'); break; case 'w': case 'x': case 'y': case 'z': phoneNumber.setCharAt(i, '9'); break; case '+': phoneNumber.setCharAt(i, '0'); break; } } return phoneNumber.toString(); } }