error, disabling serialEvent() for /dev/ttyUSB0
java.lang.reflect.InvocationTargetException
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:616)
 at processing.serial.Serial.serialEvent(Unknown Source)
 at gnu.io.RXTXPort.sendEvent(RXTXPort.java:732)
 at gnu.io.RXTXPort.eventLoop(Native Method)
 at gnu.io.RXTXPort$MonitorThread.run(RXTXPort.java:1575)
Caused by: java.lang.NullPointerException
 at PID_FrontEnd_v02.serialEvent(PID_FrontEnd_v02.java:436)
 ... 8 more 

//take the string the arduino sends us and parse it
void serialEvent(Serial myPort)
{
  
  String read = myPort.readStringUntil(10);
  if(outputFileName!="") output.print(str(millis())+ " "+read);
  String[] s = split(read, " ");
  if (s.length ==8)
  {
    Setpoint = float(s[1]);           // * pull the information
    Input = float(s[2]);              //   we need out of the
    Output = float(s[3]);             //   string and put it
    //SPLabel.setValue(s[1]);           //   where it's needed
    //InLabel.setValue(s[2]);           //
    //OutLabel.setValue(trim(s[3]));    //
    //PLabel.setValue(trim(s[4]));      //
    //ILabel.setValue(trim(s[5]));      //
    //DLabel.setValue(trim(s[6]));      //
    //AMCurrent.setValue(trim(s[7]));   //

    if(justSent)                      // * if this is the first read
    {                                 //   since we sent values to
      //SPField.setText(trim(s[1]));    //   the arduino,  take the
      //InField.setText(trim(s[2]));    //   current values and put
      //OutField.setText(trim(s[3]));   //   them into the input fields
      //PField.setText(trim(s[4]));     //
      //IField.setText(trim(s[5]));     //
      //DField.setText(trim(s[6]));     //
      mode = trim(s[7]);              //
      //AMLabel.setValue(mode);         //
      justSent=false;                 //
    }                               //

    if(!madeContact) madeContact=true;
  }
}