Unisex Bathroom - S1

import java.util.Random;
import java.util.concurrent.Semaphore;
import java.util.Set;
import java.util.HashSet;

class Demontration {
  public static void main(String[] args) throws Exception {
    UnisexBathroom bathroom = new UnisexBathroom();
    Set<Thread> threads = new HashSet<Thread>();

    for (int i = 0; i < 20; i++) {
      final int index = i;
      Thread thread =
          new Thread(
              new Runnable() {
                @Override
                public void run() {
                  try {
                    bathroom.maleWantsToGo("Male_" + index);
                  } catch (InterruptedException ie) {

                  }
                }
              });

      thread.setName("Male_" + i);
      threads.add(thread);
    }

    for (int i = 0; i < 15; i++) {
      final int index = i;
      Thread thread =
          new Thread(
              () -> {
                try {
                  bathroom.femaleWantsToGo("Female_" + index);
                } catch (InterruptedException ie) {

                }
              });
      thread.setName("Female_" + i);
      threads.add(thread);
    }

    for (Thread thread : threads) {
      thread.start();
    }

    for (Thread thread : threads) {
      thread.join();
    }
  }
}

class UnisexBathroom {
  private static final String FEMALE = "FEMALE";
  private static final String MALE = "MALE";
  private static final String NONE = "NONE";
  private static final Random random = new Random(System.currentTimeMillis());
  private static final int MAX_CAPACITY = 3;
  private static final Semaphore employeesUsingBathroom = new Semaphore(MAX_CAPACITY);

  private String currentGender = NONE;

  private void useBathRoom(String name) throws InterruptedException {
    System.out.println(name + " is using the bathroom");
    Thread.sleep(random.nextInt(100));
    System.out.println(name + " is done using the bathroom");
  }

  public void maleWantsToGo(String name) throws InterruptedException {
    synchronized (this) {
      while (currentGender.equals(FEMALE)) {
        this.wait();
      }
      currentGender = MALE;
    }
    employeesUsingBathroom.acquire();

    useBathRoom(name);

    synchronized (this) {
      employeesUsingBathroom.release();
      if (employeesUsingBathroom.availablePermits() == MAX_CAPACITY) {
        currentGender = NONE;
      }
      this.notifyAll();
    }
  }

  public void femaleWantsToGo(String name) throws InterruptedException {
    synchronized (this) {
      while (currentGender.equals(MALE)) {
        this.wait();
      }
      currentGender = FEMALE;
    }
    employeesUsingBathroom.acquire();

    useBathRoom(name);

    synchronized (this) {
      employeesUsingBathroom.release();
      if (employeesUsingBathroom.availablePermits() == MAX_CAPACITY) {
        currentGender = NONE;
      }
    }
  }
}