Yes I do. I often use Processing to send data to an Arduino. On the Arduino end I use the methods for reception as shown in Robin2's serial input basics. I format the data packets (ASCII strings) to be sent by Processing so that they can be read by the serial input basics methods. That means a start marker ('<') followed by data items separated by commas followed by an end marker ('>'). Then on the Arduino end I use the appropriate method to read in the data packet, parse the data and convert the data items as necessary to be stored in appropriate variables.