Arduino + Processing "Handshake" Issue

I have an issue getting Processing and the Arduino to talk to each other over the same Serial port. To condense my problem, I wrote a simple program where Processing sends "Processing: Hello!" every second, and the Arduino sends "Arduino: Hello there!" every second, both to the same Serial port. Here is the code:

PROCESSING CODE:

 import processing.serial.*; //import the Serial library Serial mySerial;  //the Serial port object void delay(int time) {  int start = millis();  while (millis() - start < time){} } void setup() {  size(200, 200);  println(Serial.list());  mySerial = new Serial(this, Serial.list()[9], 9600);  println(Serial.list()[9]);  mySerial.bufferUntil('\n'); } void serialEvent( Serial mySerial) {  mySerial.write("Processing: Hello!");  delay(1000); }

ARUDINO CODE:

void setup() {  Serial.begin(9600); } void loop() {  Serial.println("Arduino: Hello there!");  delay(1000); }

What I think I should be seeing in my Serial monitor on the Arduino sketch is:

"Arduino: Hello there!" "Processing: Hello!" "Arduino: Hello there!" "Processing: Hello!" "Arduino: Hello there!" "Processing: Hello!" ...

What I actually see is:

"Arduino: Hello there!" "Arduino: Hello there!" "Arduino: Hello there!" "Arduino: Hello there!" ...

Okay, so perhaps the Serial monitor only monitors Arduino output. Then, is there any other way to view the output from Processing on the Arduino side?