How to trigger a sound file in my motion sensor code?

Processing Electronics (Arduino, etc.)
1

I am trying to add a sound trigger to my code, but nothing I’ve done seems to work.
things I’ve tried:
compared strings with == and .equals
used a boolean
made the arduino send a number instead of a string to compare

here is a copy of my code:

import processing.sound.*;
static String alert="intruder alert!";
 void setup(){
 file = new SoundFile(this, "intruder.mp3");
 file.amp(0.5);
       }
  void draw(){
    while(mySerial.available() >0){

      myString = mySerial.readStringUntil(nl);//Strip data of serial port

    if(myString !=null){

  background(0);
   myVal=float(myString);
  print(myString);
  if(myString.equals(alert)){
  file.play(1);

}
}

  }
}