Here we have an application that creates a Model, which acts as a manager of a simulation. The Test class, where main is located, is where you should look for the code that does that. The Model's constructor needs a number input to set the number of agents in the model.

The aModel object then is told to buildObjects, which means it dumps agents into a list. Then it runs the "checkAgents" method, which just goes through the list of agents, telling each to run its sayHi() method.

Please note, In the checkAgents method, I show 2 ways of traversing through a collection using the Iterator. This is a vital component of Java collections and everybody must master it.