I am new to using objects - the object in the code below came from a simpler sketch and was a function that worked correctly.  The data comes in as strings from an Arduino.  I want to move up to more complex data handling and so want to move up from a function to an object.

  In the function sketch, the data is displayed correctly, but in the object sketch, the data is just zeros.

  It appears that I am not correctly passing the data into the object or not calling calling for it to be displayed.  Any observations? 

 

code:

 

import processing.serial.*;
Serial port;
//import controlP5.*;
//ControlP5 control;

DataDisplay xDataDisplay, yDataDisplay, zDataDisplay;

String coord_x = "";
String coord_y = "";
String coord_z = "";

 void setup()
 {
  size (640, 480);
  port = new Serial(this, "COM3", 9600);
  port.bufferUntil(';');

  xDataDisplay = new DataDisplay(25, 25, coord_x);
  yDataDisplay = new DataDisplay(25, 125, coord_y);
  zDataDisplay = new DataDisplay(25, 225, coord_z);
 }
 
 void serialEvent(Serial port)
 {
  //the serialEvent parses the string sent by Arduino
  //declare the serialEvent variables
  String data = "";
  int index_x = 0;
  int index_y = 0;
  int index_z = 0;
  //read the data up to the semi-colon
  data = port.readStringUntil(';');
  //trim off semi-colon
  data = data.substring(0, data.length() - 1);
  //look for the x
  index_x = data.indexOf("X");
  //fetch the x coordinate
  coord_x = data.substring(0, index_x);
  //look for the y
  index_y = data.indexOf("Y");
  //fetch the y coordinate
  coord_y = data.substring(index_x+1, index_y);
   //look for the z
  index_z = data.indexOf("Z");
  //fetch the z coordinate
  coord_z = data.substring(index_y + 1, index_z);
 }

 void draw()
 {
   background(0);
   xDataDisplay.update();
   yDataDisplay.update();
   zDataDisplay.update();
  
   xDataDisplay.display();
   yDataDisplay.display();
   zDataDisplay.display();
 }
 
 class DataDisplay
 {
  int xpos;
  int ypos;
  String coord;
  float inch_coord;
 
 
  DataDisplay(int ixpos, int iypos, String icoord)
  {
  xpos = ixpos;
  ypos = iypos;
  coord = icoord;
  }
 
  void update()
  {  
   float flt_coord = float(coord);//convert string coord to float
   float inch_coord = flt_coord/2650;//convert raw to inches
  }
 
 void display()
 {
   pushMatrix();
   translate(xpos, ypos);
   fill (0, 255, 0);
   rect(0, 0, 340, 50);
   fill(255,0,0);
   textSize(24);
   textAlign(CENTER, CENTER);
   text(inch_coord * 1, 170, 25);
   popMatrix();
 }

 }