Hello !
I'm currently working on a school project with two friends of mine, we are asked to make a video game using both Processing and Arduino.
We decided to create an avoider type of game : the player is in control of a kind of speed racer, made in Processing. We used the Arduino Light Theremin tutorial to make a sensor that will be used by the player to "drive" our speed racer.
The vehicle is supposed to be going up and down only, based on the values received from the photosensor.

Here comes our issue...
We are sending the sensorValue we're getting in Arduino to a serial port, and then we're reading it in Processing, with the intent of using it as a variable to control the Yposition of our speed racer.
Everything works fine until we try to use the variable : it's a string, and we cant seem to be able to convert it to an integer !
We are but beginners in Processing and Arduino, so we tried several codes given as exemples on the internet, hoping for an easy way to convert a string to an integer. Sadly, we are stuck with conversion errors that we cant really understand.

Below are the Arduino and Processing codes, followed by three different ways to convert that we haven't be able to use so far.


Arduino code :

1. // variable to hold sensor value
   int sensorValue;
   // variable to calibrate low value
   int sensorLow = 1023;
   // variable to calibrate high value
   int sensorHigh = 0;
   // LED pin
   const int ledPin = 13;
    
   void setup() {
     // Make the LED pin an output and turn it on
     pinMode(ledPin, OUTPUT);
     digitalWrite(ledPin, HIGH);
     // This sets up the speed connexion to the serial
     Serial.begin(9600);
   
     // calibrate for the first five seconds after program runs
     while (millis() < 5000) {
       // record the maximum sensor value
       sensorValue = analogRead(A0);
       if (sensorValue > sensorHigh) {
         sensorHigh = sensorValue;
       }
       // record the minimum sensor value
       if (sensorValue < sensorLow) {
         sensorLow = sensorValue;
       }
     }
     // turn the LED off, signaling the end of the calibration period
     digitalWrite(ledPin, LOW);
   }
   
   void loop() {
     //read the input from A0 and store it in a variable
     sensorValue = analogRead(A0);
   
     //Send sensorValue on the Serial, as an int
     Serial.println(analogRead(A0));
   
     // wait for a moment
     delay(100);
   }

Our Processing code, I'm just posting the part where we are reading the sensorValue sent to the serial :

1. import processing.serial.*;
   
   // Name of the serial port
   Serial myPort;
   
   void setup() {
     size(800, 600);
   
     // Listing all available serial ports
     println(Serial.list());
     // Matching serial port
     myPort = new Serial(this, Serial.list()[1], 9600);
   }
   
   void draw() {
     //reading serial port until \n
     String sensorValue = myPort.readStringUntil(13);
     if (sensorValue != null) {
       println(sensorValue);
     }
   }
   

-------

The value returned is 0, as if somehow the string is not converted. This is troubling for us since when we print sensorValue, the values work just fine...



2) So we tried a different way, as I said : we found the Integer.parseInt("String");

1. void draw() {
      String sensorValue = myPort.readStringUntil(13);
      // Creating an integer to store the converted string  
   
2.    int value;
           if(message != null) {
               // Using the parseInt method to convert the string to an int         
   
3.             int value = Integer.parseInt(sensorValue);
4.             println(value);
   
5.        }
6. }