Blinking Bars :0

I'm working on a project where I need to show the tempetures of 2 DS18B20's on individual bar graphs.
So far I'v been able to send the 2 tempetures from my Arduino to Processing through
through serial communication, seperate the 2 values, and "kind of" display them as bar graphs... It shows the Bar graphs for a second, and then they disappear for a second.

Is this caused by the serialEvent method ? what other approach is there?

Arduino Code:

#include <OneWire.h>
#include <DallasTemperature.h>

OneWire oneWire(10); // port 10
DallasTemperature sensors(&oneWire); // Pass our oneWire reference to Dallas Temperature.
DeviceAddress sensorA, sensorB; // arrays to hold device addresses

void setup(void)
{
  
  Serial.begin(115200); // start serial port
  sensors.begin(); // Start up the library
}

void loop(void)
{ 
  
  sensors.requestTemperatures();
  
  Serial.print(sensors.getTempCByIndex(0)); //Send SensorA data to computer
  Serial.print(","); // Seperater...
  Serial.print(sensors.getTempCByIndex(1)); //Send SensorB data to computer
  
  Serial.println();

}

Processing Code:

import processing.serial.*;
Serial myPort; // Create object from Serial class

 void setup() {  
    
  size(800, 600);   
  myPort = new Serial(this, "COM4", 115200); 
  
  myPort.bufferUntil('\n');    // read it and store it in val

}
 
 void draw(){   

  background(255);
  fill(0, 0, 255);
  
}

// serialEvent  method is run automatically by the Processing applet
// whenever the buffer reaches the  byte value set in the bufferUntil() 
// method in the setup():

void serialEvent(Serial myPort) { 
  // read the serial buffer:
  String myString = myPort.readStringUntil('\n');
  // if you got any bytes other than the linefeed:
    myString = trim(myString);
 
    // split the string at the commas
    // and convert the sections into Fahrenheit float values:
    float sensors[] = float(split(myString,','));
    float SensorB_f = ((sensors[0]*9)/5) + 32;
    float SensorA_f = ((sensors[1]*9)/5) + 32;
    
   
    //Draw Bar Graph --- BROKEN!
    rect(200, 500,20, -SensorA_f / 1.5); 
    rect(600, 500,20, -SensorB_f / 1.5);
    
    // print out the values you got:
    print("SensorA " + SensorA_f); 
    print(" , ");
    print("SensorB " + SensorB_f); 
    
    // add a linefeed after all the sensor values are printed:
    println();
 
}

All the drawing should take place in the draw() method. You can get away with drawing stuff in other methods, but if those methods are not called by draw(), when draw() runs again (and it runs in an infinite loop), draw() will erase the screen and start over.

running great now, Thanks PaulS.