Design Patterns ​
Design patterns arise as a way to deal with a often encountered problem. So a proven solution to the problem is created, this solution can now be reused during the development of software that encounters the same problem.
Observer Pattern ​
You can use the observer design pattern, when in a system, multiple entities are interested in any possible update to some particular second entity object.
Classes:
Subject: class where something happens (i.e., a change)Observer: class that should react to the change.
The Subject does not know its Observers
Also known as publish/subscribe or notification service.
In java Listeners are available.
Observer Pattern Example ​
With listeners.
Model - View - Controller (MVC) Pattern ​
MVC is a popular way of organizing your code.
The idea behind MVC is to separate your code into sections, with different purposes. Some of your code holds the data of your app, some of your code makes your app look nice, and some of your code controls how your app functions.
MVC is a way to organize your code’s core functions into their own, neatly organized boxes. This makes thinking about your app, revisiting your app, and sharing your app with others much easier and cleaner.
Model
Model objects are the domain of the application. model objects are the main components of a system.
View
View classes are the classes that interact directly with the user. This is the part of your code that makes your app look nice It can be for example a gui (graphical user interface) or a cli (command line interface)
view objects can use the Observer pattern to listen to changes to the model.
Controller
Controller code acts as a liaison between the Model and the View, receiving user input and deciding what to do with it. It’s the brains of the application, and ties together the model and the view.