Re : displaying text from serial port

e.g this is my code, the problem is that the function writetext in Draw would display text with every new value in new line(which is fine), but i want to keep displaying all the values i get instead of just displaying the latest value recieved.

///////////////////////////////////////

import processing.serial.*;

Serial myPort;

String gps_error = "";

PFont font;

int widthadd = 30 , heightadd = 30 ;

void setup() {

  size(1000,500);

  myPort = new Serial(this, Serial.list()[0], 9600);

  myPort.bufferUntil('\n');

  font = createFont(PFont.list()[2],10);

  textFont(font);

}

void draw() 

{

      writeText("GPS Error reading = " + gps_error ); //want to keep the older one and then display next

}

void serialEvent (Serial myPort){

 

  gps_error = myPort.readStringUntil('\n');

  

 // if(gps_error != null){

   // gps_error=trim(gps_error);

  

// }

heightadd = heightadd + 30 ;

if (heightadd == 450)

{

  heightadd= 30 ;

  widthadd= 200;

}

  

  }

  

void writeText(String textToWrite)

{    

  background(255);

  fill(0);

  text(textToWrite, widthadd, heightadd);   

}