Arduino piano stair Processing script

sound.pde

import processing.serial.*;
import ddf.minim.signals.*; // Minim sound library
import ddf.minim.*;
import ddf.minim.analysis.*;
import ddf.minim.effects.*;
int prevent = 0; // Double ring prevention
Serial myPort;  // The serial port
Minim minim;

AudioPlayer a;
AudioPlayer b;
AudioPlayer c;

void setup() {
  // List all the available serial ports:
  println(Serial.list());
  minim = new Minim(this);
  int prevent = 0;

  a = minim.loadFile("15.mp3"); // Stair 15
  b = minim.loadFile("14.mp3"); // Stair 14
  c = minim.loadFile("13.mp3"); // Stair 13

  // I know that the first port in the serial list on my mac
  // is always my  Keyspan adaptor, so I open Serial.list()[0].
  // Open whatever port is the one you're using.
  myPort = new Serial(this, Serial.list()[0], 9600);
  myPort.bufferUntil('\n');
}

void draw() {
  while (myPort.available () > 0) {
    String inBuffer = myPort.readStringUntil('\n');

    if (inBuffer != null) {
      if (inBuffer.contains("#0#") && prevent != 0) {
        a.rewind(); 
        a.play();
        prevent = 0;
      } 
      if (inBuffer.contains("#1#")  && prevent != 1) {
        b.rewind(); 
        b.play();
        prevent = 1;
      } 
      if (inBuffer.contains("#2#") && prevent != 2) {
        c.rewind(); 
        c.play();
        prevent = 2;
      } 
    }
  }
}