Solution to Bug Patrol #1

bug_patrol1_solution.java

// ...

if (!this.serialsSet.contains(serial)) { // if (!flag) {
  this.serialsSet.add(serial); // flag = true;
  Runnable task = new Runnable() {
    /** {@inheritDoc} */
    @Override
    public void run() {
      // Use try-finally. Before the thread dies, it will reset the boolean variable.
      try {
        processSerial(serial);
      }
      finally {
        serialsSet.remove(serial); // flag = false;
      }
    }
  };
  this.scheduler.schedule(task, NUM_SECONDS,
  TimeUnit.SECONDS);
}

// ...