Sleeping barber problem using Semaphores

Problem Statement: 

The barber has one barber chair and a waiting room with a number of chairs in it. When the barber finishes cutting a customer's hair, he dismisses the customer and then goes to the waiting room to see if there are other customers waiting. If there are, he brings one of them back to the chair and cuts his hair. If there are no other customers waiting, he returns to his chair and sleeps in it.

Each customer, when he arrives, looks to see what the barber is doing. If the barber is sleeping, then the customer wakes him up and sits in the chair. If the barber is cutting hair, then the customer goes to the waiting room. If there is a free chair in the waiting room, the customer sits in it and waits his turn. If there is no free chair, then the customer leaves.

package com.concurrency;

import java.util.concurrent.Semaphore;

public class SleepingBarber extends Thread {

 /* PREREQUISITES */

 /*
  * we create the semaphores. First there are no customers and the barber is
  * asleep so we call the constructor with parameter 0 thus creating
  * semaphores with zero initial permits. Semaphore(1) constructs a binary
  * semaphore, as desired.
  */

 public static Semaphore customers = new Semaphore(0);
 public static Semaphore barber = new Semaphore(0);
 public static Semaphore accessSeats = new Semaphore(1);

 /* we denote that the number of chairs in this barbershop is 5. */

 public static final int CHAIRS = 5;

 /*
  * we create the integer numberOfFreeSeats so that the customers can either
  * sit on a free seat or leave the barbershop if there are no seats
  * available
  */

 public static int numberOfFreeSeats = CHAIRS;

 /* THE CUSTOMER THREAD */

 class Customer extends Thread {

  /*
   * we create the integer iD which is a unique ID number for every
   * customer and a boolean notCut which is used in the Customer waiting
   * loop
   */

  int iD;
  boolean notCut = true;

  /* Constructor for the Customer */

  public Customer(int i) {
   iD = i;
  }

  public void run() {
   while (notCut) { // as long as the customer is not cut
    try {
     accessSeats.acquire(); // tries to get access to the chairs
     if (numberOfFreeSeats > 0) { // if there are any free seats
      System.out.println("Customer " + this.iD
        + " just sat down.");
      numberOfFreeSeats--; // sitting down on a chair
      customers.release(); // notify the barber that there is
            // a customer
      accessSeats.release(); // don't need to lock the chairs
            // anymore
      try {
       barber.acquire(); // now it's this customers turn
            // but we have to wait if the
            // barber is busy
       notCut = false; // this customer will now leave
           // after the procedure
       this.get_haircut(); // cutting...
      } catch (InterruptedException ex) {
      }
     } else { // there are no free seats
      System.out.println("There are no free seats. Customer "
        + this.iD + " has left the barbershop.");
      accessSeats.release(); // release the lock on the seats
      notCut = false; // the customer will leave since there
          // are no spots in the queue left.
     }
    } catch (InterruptedException ex) {
    }
   }
  }

  /* this method will simulate getting a hair-cut */

  public void get_haircut() {
   System.out.println("Customer " + this.iD
     + " is getting his hair cut");
   try {
    sleep(5050);
   } catch (InterruptedException ex) {
   }
  }

 }

 /* THE BARBER THREAD */

 class Barber extends Thread {

  public Barber() {
  }

  public void run() {
   while (true) { // runs in an infinite loop
    try {
     customers.acquire(); // tries to acquire a customer - if
           // none is available he goes to
           // sleep
     accessSeats.acquire(); // at this time he has been awaken ->
           // want to modify the number of
           // available seats
     numberOfFreeSeats++; // one chair gets free
     barber.release(); // the barber is ready to cut
     accessSeats.release(); // we don't need the lock on the
           // chairs anymore
     this.cutHair(); // cutting...
    } catch (InterruptedException ex) {
    }
   }
  }

  /* this method will simulate cutting hair */

  public void cutHair() {
   System.out.println("The barber is cutting hair");
   try {
    sleep(5000);
   } catch (InterruptedException ex) {
   }
  }
 }

 /* main method */

 public static void main(String args[]) {

  SleepingBarber barberShop = new SleepingBarber(); // Creates a new
               // barbershop
  barberShop.start(); // Let the simulation begin
 }

 public void run() {
  Barber giovanni = new Barber(); // Giovanni is the best barber ever
  giovanni.start(); // Ready for another day of work

  /* This method will create new customers for a while */

  for (int i = 1; i < 16; i++) {
   Customer aCustomer = new Customer(i);
   aCustomer.start();
   try {
    sleep(2000);
   } catch (InterruptedException ex) {
   }
   ;
  }
 }
}