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The MVC pattern stands for Model-View-Controller pattern. This pattern is used for separating an application into three main logical components: the model, the view, and the controller. * **Model** - The model represents an object carrying data. It can also contain logic to update the controller if its data changes. * **View** - The view represents the visualization of the data that model contains. * **Controller** - The controller acts on both model and view. It controls the data flow into model object and updates the view whenever data changes. It keeps view and model separate. !(#) * * * ## Summary ### Intent Separate an application's concerns by dividing it into three core components: Model, View, and Controller. ### Problem It Solves * It solves the problem of coupling business logic, data, and interface display within an application, making development and maintenance clearer and simpler. ### When to Use * When there is a need to separate data, business logic, and interface display for independent development and maintenance. ### Implementation * **Model**: Responsible for data and business logic, typically including data storage, retrieval, and business rules. * **View**: Responsible for the user interface that displays the data (model), containing no business logic. * **Controller**: Receives user input, invokes the model and view to fulfill the user's request. ### Key Code * **Model**: Contains business logic and data state. * **View**: Contains presentation logic, rendering the model's data into a user interface. * **Controller**: Contains logic to respond to user input and update the model and view. ### Application Example * **Web Application**: A user sends a request through a browser (view), the server-side controller processes the request, and the model performs data processing. ### Advantages * **Separation of Concerns**: Separates data, business logic, and interface display, reducing coupling. * **Easy Maintenance**: Each component is responsible for a specific task, facilitating independent development and maintenance. * **Scalability**: The model, view, or controller can be replaced or updated independently. ### Disadvantages * **May Increase Complexity**: For simple projects, introducing MVC might add unnecessary complexity. * **Performance Issues**: If not used correctly, it can lead to performance problems. ### Usage Suggestions * Consider using the MVC pattern when developing large applications that require a clear separation of data, business logic, and user interface. ### Notes * Ensure the interactions between the model, view, and controller are clear to avoid interdependencies. ### Main Roles Involved * **Model**: * Manages data and business logic. * **View**: * Displays the data from the model, providing the user interface. * **Controller**: * Receives user input, invokes the model and view for processing. * **User (Optional)**: * Interacts with the view, triggering the application's flow. * * * ## Implementation We will create a _Student_ object as the model. _StudentView_ is a view class that prints student details to the console, and _StudentController_ is a controller class responsible for storing data in the _Student_ object and updating the view _StudentView_ accordingly. _MVCPatternDemo_, our demo class, uses _StudentController_ to demonstrate the usage of the MVC pattern.  ## Step 1 Create the model. ## Student.java public class Student{private String rollNo; private String name; public String getRollNo(){return rollNo; }public void setRollNo(String rollNo){this.rollNo = rollNo; }public String getName(){return name; }public void setName(String name){this.name = name; }} ## Step 2 Create the view. ## StudentView.java public class StudentView{public void printStudentDetails(String studentName, String studentRollNo){System.out.println("Student: "); System.out.println("Name: " + studentName); System.out.println("Roll No: " + studentRollNo); }} ## Step 3 Create the controller. ## StudentController.java public class StudentController{private Student model; private StudentView view; public StudentController(Student model, StudentView view){this.model = model; this.view = view; }public void setStudentName(String name){model.setName(name); }public String getStudentName(){return model.getName(); }public void setStudentRollNo(String rollNo){model.setRollNo(rollNo); }public String getStudentRollNo(){return model.getRollNo(); }public void updateView(){view.printStudentDetails(model.getName(), model.getRollNo()); }} ## Step 4 Use _StudentController_ methods to demonstrate the usage of the MVC design pattern. ## MVCPatternDemo.java public class MVCPatternDemo{public static void main(String[]args){Student model = retrieveStudentFromDatabase(); StudentView view = new StudentView(); StudentController controller = new StudentController(model, view); controller.updateView(); controller.setStudentName("John"); controller.updateView(); }private static Student retrieveStudentFromDatabase(){Student student = new Student(); student.setName("Robert"); student.setRollNo("10"); return student; }} ## Step 5 Execute the program, and the output will be: Student: Name: RobertRoll No: 10Student: Name: JohnRoll No: 10