Model-View-Presenter (MVP) Pattern

The Model-View-Presenter (MVP) pattern is a software architectural pattern used primarily for designing the structure of user interfaces.

MVP separates the application into three components: Model, View, and Presenter, promoting a clean separation of concerns.

• Model: Represents the data and business logic of the application.
• View: Displays the data (UI) and forwards user actions to the Presenter.
• Presenter: Acts as a mediator between the Model and the View, handling the logic and updating the View.

In MVP, the flow of control is as follows:

graph TD;
    A[User Interaction] --> B[View];
    B --> C[Presenter];
    C --> D[Model];
    D --> C;
    C --> B;
    B --> A;
            

The workflow of the MVP pattern can be summarized in the following steps:

1. User interacts with the View.
2. The View forwards the interaction to the Presenter.
3. The Presenter processes the data and interacts with the Model if necessary.
4. The Model returns data to the Presenter.
5. The Presenter updates the View with new data.

Here is a basic implementation example of the MVP pattern in Java:

interface View {
    void showData(String data);
}

class Model {
    String getData() {
        return "Hello, MVP!";
    }
}

class Presenter {
    private View view;
    private Model model;

    Presenter(View view) {
        this.view = view;
        this.model = new Model();
    }

    void updateView() {
        String data = model.getData();
        view.showData(data);
    }
}

class MainView implements View {
    public void showData(String data) {
        System.out.println(data);
    }

    public static void main(String[] args) {
        MainView mainView = new MainView();
        Presenter presenter = new Presenter(mainView);
        presenter.updateView();
    }
}
                

• Keep the View as simple as possible, focusing only on displaying data.
• Ensure that the Presenter is responsible for all business logic.
• Use interfaces to define the communication between the View and the Presenter.
• Test the Presenter independently of the View by using mock objects.