AnyLogic agent-based modelling: ClassCastException

Question

I am working with an agent-based simulation of an infectious disease epidemic in AnyLogic. I have two agents types in my model- Person and Building. I'm trying to write a function that counts the number of infectious contacts that the agent type 'Person' has at any given point in time. Below is my code for the function:

int infectedConnections = 0;

if (getConnections() != null)
    for (Agent a : this.getConnections())
        {
        Person p = (Person) a;

        if (p.IsCurrentlyInfected()) 
            infectedConnections++;
            }

return infectedConnections ;

The code compiles without any errors but during runtime, it throws up a java.lang.ClassCastException with the message: model.Building cannot be cast to model.Person.

When I try the same code with just one agent type (i.e. 'Person'), the model runs fine and the function returns the correct value. Could someone tell me how I could rectify my code so that I am able to run the function for 'Person' please?

Answer 1

If you just want to ignore agents of type Building, then you can do the following:

int infectedConnections = 0;

if (getConnections() != null) {
    for (Agent a : this.getConnections())
    {
        if(a instanceof Person) {
            Person p = (Person) a;

            if (p.IsCurrentlyInfected()) {
               infectedConnections++;
            }
        }
    }
}
return infectedConnections;

The problem is that (Person) a; will fail if a is a Building instead of a Person.