Describe the MVC Connection. How is this design pattern implemented in Java Swing applications?

Describe the MVC Connection. How is this design pattern implemented in Java Swing applications?

Answer:-

MVC Connection in Java Swing

MVC stands for Model-View-Controller. It is a design pattern used to separate the application logic into three interconnected components. This separation helps manage complexity, improves maintainability, and promotes reusability.

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1. Components of MVC

Component	Responsibility
Model	Manages data and business logic
View	Displays UI to the user
Controller	Handles user input and interacts with the model and view

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2. MVC in Java Swing

In Swing, MVC is partially implemented internally. Swing components like JTable, JList, JTree use MVC, where:

• Model handles data (e.g., TableModel, ListModel)
• View is the visual component (e.g., JTable, JList)
• Controller is often implicit (event listeners)

However, you can also explicitly implement MVC in custom applications.

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3. MVC Example: Simple Login Window

Model (Logic)

public class LoginModel {
    public boolean authenticate(String username, String password) {
        return username.equals("admin") && password.equals("1234");
    }
}

View (UI)

import javax.swing.*;

public class LoginView extends JFrame {
    JTextField usernameField = new JTextField(10);
    JPasswordField passwordField = new JPasswordField(10);
    JButton loginButton = new JButton("Login");
    JLabel resultLabel = new JLabel();

    public LoginView() {
        setTitle("Login");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setSize(300, 150);
        setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));

        add(new JLabel("Username:"));
        add(usernameField);
        add(new JLabel("Password:"));
        add(passwordField);
        add(loginButton);
        add(resultLabel);

        setVisible(true);
    }
}

Controller (Glue Logic)

import java.awt.event.*;

public class LoginController {
    public LoginController(LoginView view, LoginModel model) {
        view.loginButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String user = view.usernameField.getText();
                String pass = new String(view.passwordField.getPassword());

                if (model.authenticate(user, pass)) {
                    view.resultLabel.setText("Login successful!");
                } else {
                    view.resultLabel.setText("Invalid credentials.");
                }
            }
        });
    }
}

Main Class to Run

public class MVCDemo {
    public static void main(String[] args) {
        LoginView view = new LoginView();
        LoginModel model = new LoginModel();
        new LoginController(view, model);
    }
}

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Summary of MVC in Swing

• Model = business logic and data
• View = UI components (Swing widgets)
• Controller = connects user actions to model and updates the view