question: private static String tryHashStringSha256 ( Context context , String input ) { String salt = createSalt ( context ) ; try { MessageDigest hash = MessageDigest . getInstance ( "SHA-256" ) ; hash . reset ( ) ; hash . update ( input . getBytes ( ) ) ; hash . update ( salt . getBytes ( ) ) ; byte [ ] hashedBytes = hash . digest ( ) ; return bytesToHex ( hashedBytes ) ; } catch ( NoSuchAlgorithmException e ) { return input ; } }
target:  Get a SHA-256 hash of the input string if the algorithm is available. If the algorithm is unavailable, return empty string.