MVC Pattern

Model View Controller

Model: The model makes use of the Observer Pattern so that

it can keep observers updated yet stay decoupled from them.

● Controller: The controller is the strategy for the view. The view

can use different implementations of the controller to get

different behavior.

● View: The view uses the Composite Pattern to implement the

user interface, which usually consists of nested components like

panels, frames and buttons.

Create Model

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;
   }
}

Create View

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);
   }
}

Create Controller

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());
   } 
}

Demo

public class MVCPatternDemo {
   public static void main(String[] args) {

      //fetch student record based on his roll no from the database
      Student model  = retriveStudentFromDatabase();

      //Create a view : to write student details on console
      StudentView view = new StudentView();

      StudentController controller = new StudentController(model, view);

      controller.updateView();

      //update model data
      controller.setStudentName("John");

      controller.updateView();
   }

   private static Student retriveStudentFromDatabase(){
      Student student = new Student();
      student.setName("Robert");
      student.setRollNo("10");
      return student;
   }
}