### Question:
WalletUtils { public static boolean isValidAddress(String input) { String cleanInput; try{ byte [] bytes = Bech32.addressDecode(input); String hexAddress = Hex.toHexString(bytes); cleanInput = Numeric.cleanHexPrefix(hexAddress); }catch (Exception e){ return false; } try { Numeric.toBigIntNoPrefix(cleanInput); } catch (NumberFormatException e) { return false; } return cleanInput.length() == ADDRESS_LENGTH_IN_HEX; }  static String generateFullNewWalletFile(String password, File destinationDirectory); static String generateLightNewWalletFile(String password, File destinationDirectory); static String generatePlatONWalletFile(String password, File destinationDirectory); static Bip39Wallet generatePlatONBip39Wallet(String password, File destinationDirectory); static String generatePlatONWalletFile(String password, ECKeyPair ecKeyPair, File destinationDirectory); static String generateNewWalletFile(String password, File destinationDirectory); static String generateNewWalletFile(
            String password, File destinationDirectory, boolean useFullScrypt); static String generateWalletFile(
            String password, ECKeyPair ecKeyPair, File destinationDirectory, boolean useFullScrypt); static Bip39Wallet generateBip39Wallet(String password, File destinationDirectory); static Credentials loadCredentials(String password, String source); static Credentials loadCredentials(String password, File source); static Credentials loadBip39Credentials(String password, String mnemonic); static String getDefaultKeyDirectory(); static String getTestnetKeyDirectory(); static String getMainnetKeyDirectory(); static String getRinkebyKeyDirectory(); static boolean isValidPrivateKey(String privateKey); static boolean isValidAddress(String input);  }### Answer:
@Test public void testIsValidAddress() { assertTrue(isValidAddress(BECH32_ADDRESS.getMainnet())); assertFalse(isValidAddress("")); assertFalse(isValidAddress(BECH32_ADDRESS.getMainnet() + 'a')); assertFalse(isValidAddress(BECH32_ADDRESS.getMainnet().substring(1))); }