Processing + Arduino, serial communication

Hi,

I have what I think is one of the simplest things you can do with the Arduino and Processing.

My Arduino program opens up a com port, writes a number (using Serial.println()), and then delays for a bit. Repeat.

On the Processing side I create a new Serial object (using the same com port and baud rate the Arduino is configured to) and then wait for data using readStringUntil('\n').

Everything is fine on the Arduino side - I can see what I expect in the Serial Monitor. But as soon as I start the Processing side of the equation there are tons of extra digits sent to the Arduino's Serial Monitor window???

Would someone please check out my code to see if I am doing something ridiculous? Also, I should mention that every time I start my Processing app this message is reported: "RXTX Warning: Removing stale lock file. /var/lock/LK.046.018.014".

Thanks!
LT

Arduino side:

void setup()
{
  Serial.begin(9600);
}

void loop()
{
  Serial.println(10);
  delay(500);
}

Processing side:

import processing.serial.*;

Serial g_port;

void setup() 
{
  size(480, 120);

  // This is the serial port that the Arduino opens  
  g_port = new Serial(this, "/dev/tty.usbmodem1421", 9600);
  g_port.bufferUntil('\n'); 
}

void draw() 
{
  // Nothing going on yet
}

void serialEvent (Serial port)
{
  int val = int(port.readStringUntil('\n'));
}

Everything is fine on the Arduino side - I can see what I expect in the Serial Monitor. But as soon as I start the Processing side of the equation there are tons of extra digits sent to the Arduino's Serial Monitor window???

The Arduino can talk to the Processing application OR the Serial Monitor. Not both.

Thank you!