question: public static String generateChatId ( final String receiverId , final String senderId ) { String combined = null ; if ( receiverId . compareTo ( senderId ) < 0 ) { combined = String . format ( Locale . US , AppConstants . CHAT_ID_FORMAT , receiverId , senderId ) ; } else { combined = String . format ( Locale . US , AppConstants . CHAT_ID_FORMAT , senderId , receiverId ) ; } String hashed = null ; try { hashed = Utils . sha1 ( combined ) ; } catch ( final NoSuchAlgorithmException e ) { hashed = combined ; } return hashed ; }
target:  Generates as chat ID which will be unique for a given sender/receiver pair