MVC (Model‐View‐Controller)

In a typical Java MVC (Model-View-Controller) application, structuring classes for high maintainability involves adhering to design principles and best practices. Here are some recommendations:

1. Clear Separation of Concerns:

• Model: Contains classes responsible for data and business logic. Keep models simple, focused, and free from presentation-related code.
• View: Contains classes responsible for user interface components. Keep views focused on displaying data and receiving user input. Avoid putting business logic in views.
• Controller: Contains classes responsible for handling user input and updating the model and view accordingly. Controllers should not contain significant business logic; delegate that to the model.

2. Use Interfaces:

• Define interfaces for models, views, and controllers. This promotes loose coupling and allows for easier replacement or extension of components without affecting the rest of the application.

3. Model:

• Single Responsibility Principle (SRP): Each model class should have a single responsibility. If a class becomes too large or handles too many responsibilities, consider breaking it into smaller, more focused classes.
• Encapsulation: Encapsulate the internal state of model classes and expose it through well-defined methods. Avoid exposing internal details directly.

4. View:

• Keep Views Dumb: Views should focus on displaying data and handling user input. Minimize business logic in views to ensure maintainability.
• Avoid Direct Model Access: Views should not directly access or manipulate the model. Use controllers to mediate between views and models.

5. Controller:

• Handle User Input: Controllers should handle user input, interpret it, and update the model and view accordingly. Avoid putting business logic in controllers; delegate that to the model.
• Delegate to Services: For complex business logic, consider creating service classes that the controller can delegate to. This keeps controllers focused on user input handling.

6. Dependency Injection:

• Use dependency injection to provide necessary dependencies to classes. This makes it easier to replace components and promotes testability.

7. Unit Testing:

• Design classes with unit testing in mind. Keep classes small, focused, and independent to facilitate easier unit testing.

8. Document Code:

• Provide clear and concise documentation for classes, methods, and important components. This helps new developers understand the codebase and aids in maintenance.

9. Consistent Naming and Coding Conventions:

• Follow consistent naming conventions and coding styles. This makes the codebase more readable and helps developers understand the structure and purpose of classes.

10. Version Control and Branching:

• Use version control systems (e.g., Git) to track changes and manage the evolution of the codebase. Create feature branches for new development or bug fixes, and merge them back into the main branch after testing.

Example Structure:

- com.example.mvcapp
  - model
    - UserModel.java
    - UserService.java
  - view
    - UserView.java
  - controller
    - UserController.java
  - app
    - MainApp.java

This is just a basic example, and the actual structure will depend on the complexity of your application. The key is to keep components modular, focused, and adhere to the principles of separation of concerns and single responsibility.