Example Discrete Event Simulation

A traffic light cycles through green, yellow, and red; this can easily be simulated:

public static void
  red (PriorityQueue pq, int time) {
      turnOff("green");
      turnOff("yellow");
      turnOn("red");
      pq.add(new Event("green", time + 60));
      }

This program is typical of Discrete Event Simulation:

• It may examine the state of the world at the time it is executed.

• It performs one or more simple actions, in this case turning on the red light and turning off the others.

• It schedules one or more new events for future times, i.e. the green event for the current time plus 60 seconds.