Thank you for reading my first post. This question relates to the Simple Write serial example.
String portName = Serial.list(); myPort = new Serial(this, portName, 9600);
This doesn’t find the correct port but it does if I change  to  or do the following:
myPort = new Serial(this, "/dev/ttyUSB0", 9600);
I’m inclined to use the latter, is that the correct approach?
Also, processing, again using the simple write example, continually sends serial data to the Arduino. Is that the way it should work? Moving the mouse over the circle does send the correct data and does turn the led on and off but I’m concerned about the continual sending of data. I expected data to be sent only while the mouse is over the circle.