During this week I refactored titiritero and in particular the implementation of the gameloop.  The gameloop is a control structure that runs the simulation (give live to model) and updates the views. There are to ways of implementing it:

The first one, is with an infinite loop with a Thread.sleep inside, something like this:

shouldExecuteGameloop = true;
while(shouldExecuteGameloop ){
   this.runSimulation();
   this.updateView();
   Thread.sleep(simulationInterval);
}

The other alternative is using a Timer object and making the gameloop class to implement TimerTask interface, something like this:

Timer timer = new Timer(gameloop);
timer.start(simulationInterval);
...
gameloop.onTimerTask(){
   this.runSimulation();
   this.updateView();
}

I choose the first alternative because with the second one it could happen that the execution of a single loop of the gameloop takes to much time, so there could be more than one thread working simultaneously on the same object, producing an anomalous behaviors of the application.