Java Design Patterns Tutorial - Java Design Pattern - MVC Pattern

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MVC Pattern stands for Model-View-Controller Pattern.

From the name we can see that the MVC pattern involves three parts:

• Model - Model represents an object carrying data. It can also have logic to update controller if its data changes.

• View - View represents the visualization of the data that model contains. Usually it has the UI logic.

• Controller - Controller references 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.

Example

class Employee {//from  w  w w. j  av  a  2 s. co m
  private String id;
  private String name;

  public String getId() {
    return id;
  }

  public void setId(String id) {
    this.id = id;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }
}

class EmployeeView {
  public void printEmployeeDetails(String name, String no) {
    System.out.println("Employee: ");
    System.out.println("Name: " + name);
    System.out.println("ID: " + no);
  }
}

class EmployeeController {
  private Employee model;
  private EmployeeView view;

  public EmployeeController(Employee model, EmployeeView view) {
    this.model = model;
    this.view = view;
  }

  public void setEmployeeName(String name) {
    model.setName(name);
  }

  public String getEmployeeName() {
    return model.getName();
  }

  public void setEmployeeId(String rollNo) {
    model.setId(rollNo);
  }

  public String getEmployeeId() {
    return model.getId();
  }

  public void updateView() {
    view.printEmployeeDetails(model.getName(), model.getId());
  }
}

public class Main {
  public static void main(String[] args) {
    Employee model = new Employee();
    model.setName("Tom");
    model.setId("1");
    EmployeeView view = new EmployeeView();

    EmployeeController controller = new EmployeeController(model, view);
    controller.updateView();
    controller.setEmployeeName("New Name");
    controller.updateView();
  }
}

The code above generates the following result.

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