question: public static long subAddressToLong ( final String subaddress ) { Preconditions . checkNotNull ( subaddress , "Argument subaddress can't be null." ) ; if ( subaddress . contains ( "." ) ) { final String [ ] parts = subaddress . split ( "\\." ) ; Preconditions . checkArgument ( parts . length == 2 , "Argument subaddress is not a valid subaddress." ) ; final long firstPart = Long . parseLong ( parts [ 0 ] ) ; final long secondPart = Long . parseLong ( parts [ 1 ] ) ; return ( firstPart * 0x100 ) + secondPart ; } else { throw new IllegalArgumentException ( "Argument subaddress is not a valid subaddress." ) ; } }
target:  Converts a string that contains a subaddress into a long value with the same offset as the string. Attention: A valid subaddress of the form "number.number" must be passed to the function or an exception is thrown.