Talking to different classes

I have 4 classes: a navigation class, a class triggered by a navigation click, another class which is triggered from the previous class and a final class displaying an object.

What I can’t work out is how to comunicate between the navigation class and the final class. What I’d like is for the navigation to know that the final class has being displayed, i.e. once the navigation is clicked, while the final class is displaying, the navigation can remove the final class from the display list.

Do I set up a Boolean variable in each class, with the variable set to true once the final class is added and an if statement in the navigation class (if the Boolean is set to false, removeChild(finalclass)? This would mean a function and variable in each class… :h:and I cant even get this to work :h: my methods are pointing in the wrong direction so to speak…Is there an easier way of each class finding out about what has been added and therefore what can be removed, without all these functions and calls to different classes?