Java Phaser repeat a series of tasks

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Phaser;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.AtomicInteger;

public class Main {
   private void execute() {
      List<Entity> entities = new ArrayList<>();
      entities = new ArrayList<>();
      entities.add(new Developer());
      entities.add(new Tester());
      entities.add(new Tester());
      entities.add(new Tester());
      gameEngine(entities);//from w w  w. j a  v  a2s  . c  o  m
   }

   private void gameEngine(List<Entity> entities) {
      // Using a phaser to repeat a series of tasks
      final int iterations = 3;  
      Phaser phaser = new Phaser(1) {
          protected boolean onAdvance(int phase, int registeredParties) {
              System.out.println("Phase number " + phase + " completed\n");                
              return phase >= iterations-1 || registeredParties == 0;
          }
      };
      for (final Entity entity : entities) {
          final String member = entity.toString();
          System.out.println(member + " joined the game");
          phaser.register();
          new Thread() {

              @Override
              public void run() {
                  do {
                      System.out.println(member + " starting run");
                      entity.run();
                      System.out.println(member + 
                              " waiting for the remaining participants during phase " +
                              phaser.getPhase());
                      phaser.arriveAndAwaitAdvance(); // wait for remaining entities
                  } while (!phaser.isTerminated());
              }
          }.start();
      }

      while (!phaser.isTerminated()) {
          phaser.arriveAndAwaitAdvance();
      }
      System.out.println("Phaser continuing");
   }

   public static void main(String[] args) {
      new Main().execute();
   }

}

abstract class Entity implements Runnable {
   public abstract void run();
}

class Developer extends Entity implements Runnable {
   private final static AtomicInteger idSource = new AtomicInteger();
   private final int id = idSource.incrementAndGet();

   public void run() {
      System.out.println(toString() + " started");
      try {
         Thread.currentThread().sleep(ThreadLocalRandom.current().nextInt(200, 600));
      } catch (InterruptedException ex) {
         ex.printStackTrace();
      }
      System.out.println(toString() + " stopped");
   }

   @Override
   public String toString() {
      return "Developer #" + id;
   }
}

class Tester extends Entity implements Runnable {
   private final static AtomicInteger idSource = new AtomicInteger();
   private final int id = idSource.incrementAndGet();

   public void run() {
      System.out.println(toString() + " started");
      try {
         Thread.currentThread().sleep(ThreadLocalRandom.current().nextInt(400, 800));
      } catch (InterruptedException ex) {
         ex.printStackTrace();
      }
      System.out.println(toString() + " stopped");
   }

   @Override
   public String toString() {
      return "Tester #" + id;
   }
}