== public static void isValidMove(String from, String to) { 1. if ((from null || from.trim().isEmpty()) || (to == null || to.tr im().isEmpty()) { // A 2. return "Invalid: and both needs to be non-empty str ings" ; 3. } 4. 5. if (from.equals("stock") && isValidPileNumber(to)) { // B 6. return "Valid: stock to pile" 7. } else if (from.equals("stock") && SUITS.contains(to)) { // C 8. return "Valid: stock to suit" 9. } else if (isValidPileNumber(from)) { // D 10. if (!(isValidPileNumber(to) || SUITS.contains(to))) { // E 11. return "Invalid: value is invalid"; 12. } 13. return "Valid: pile to (pile or suit)" 14. } 15. return "Invalid or value"; } // Helper variables and methods public static final Collection SUITS = Arrays.asList("s", "d", "h ", "C"); > public static boolean isValidPileNumber (String input) { try { int i = Integer.parseInt(input.trim()); return i >= 1 && i