QuizApp.java

package example;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class QuizApp {
    private JFrame frame;
    private JPanel loginPanel, quizPanel;
    private JTextField usernameField;
    private JPasswordField passwordField;
    private JButton loginButton, submitButton;
    private JLabel questionLabel;
    private JRadioButton[] optionButtons;
    private ButtonGroup optionGroup;
    private int currentQuestion = 0;
    private int score = 0;

    private String[][] questions = {
        {"What is the capital of France?", "Berlin", "Madrid", "Paris", "Rome", "Paris"},
        {"Which planet is known as the Red Planet?", "Earth", "Mars", "Jupiter", "Saturn", "Mars"},
        {"What is the pink city of India?", "Hyderabad", "Mumbai", "Jaipur", "Lucknow", "Jaipur"},
        {"What is the capital city of South Korea?", "Bangkok", "Seoul", "Beijing", "Tokyo", "Seoul"}
    };

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            try {
                QuizApp app = new QuizApp();
                app.createUI();
            } catch (Exception e) {
                e.printStackTrace();
            }
        });
    }

    public void createUI() {
        frame = new JFrame("Quiz App");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500, 400);
        frame.setLayout(new CardLayout());

        // Login Panel
        loginPanel = new JPanel();
        loginPanel.setLayout(new GridLayout(4, 2, 10, 10));
        loginPanel.setBackground(Color.CYAN);

        JLabel usernameLabel = new JLabel("Username:");
        usernameField = new JTextField(15);
        JLabel passwordLabel = new JLabel("Password:");
        passwordField = new JPasswordField(15);
        loginButton = new JButton("Login");

        loginPanel.add(usernameLabel);
        loginPanel.add(usernameField);
        loginPanel.add(passwordLabel);
        loginPanel.add(passwordField);
        loginPanel.add(new JLabel()); // Empty label for spacing
        loginPanel.add(new JLabel()); // Empty label for spacing
        loginPanel.add(loginButton);

        frame.add(loginPanel, "Login");

        // Quiz Panel
        quizPanel = new JPanel();
        quizPanel.setLayout(new BoxLayout(quizPanel, BoxLayout.Y_AXIS));

        questionLabel = new JLabel("");
        questionLabel.setFont(new Font("Arial", Font.PLAIN, 16));
        quizPanel.add(questionLabel);

        optionButtons = new JRadioButton[4];
        optionGroup = new ButtonGroup();
        for (int i = 0; i < 4; i++) {
            optionButtons[i] = new JRadioButton();
            optionButtons[i].setFont(new Font("Arial", Font.PLAIN, 14));
            optionGroup.add(optionButtons[i]);
            quizPanel.add(optionButtons[i]);
        }

        submitButton = new JButton("Submit");
        quizPanel.add(submitButton);

        frame.add(quizPanel, "Quiz");

        frame.setVisible(true);

        // Action listeners
        loginButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                login();
            }
        });

        submitButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                submitAnswer();
            }
        });
    }

    private void login() {
        String username = usernameField.getText();
        String password = new String(passwordField.getPassword());

        if ("user".equals(username) && "pass".equals(password)) {
            CardLayout cl = (CardLayout) frame.getLayout();
            cl.show(frame.getContentPane(), "Quiz");
            loadQuestion();
        } else {
            JOptionPane.showMessageDialog(frame, "Invalid username or password.", "Error", JOptionPane.ERROR_MESSAGE);
        }
    }

    private void loadQuestion() {
        if (currentQuestion < questions.length) {
            String[] questionData = questions[currentQuestion];
            questionLabel.setText(questionData[0]);
            for (int i = 0; i < 4; i++) {
                optionButtons[i].setText(questionData[i + 1]);
            }
            optionGroup.clearSelection();
        } else {
            showResult();
        }
    }

    private void submitAnswer() {
        String selectedOption = null;
        for (JRadioButton optionButton : optionButtons) {
            if (optionButton.isSelected()) {
                selectedOption = optionButton.getText();
                break;
            }
        }

        if (selectedOption == null) {
            JOptionPane.showMessageDialog(frame, "Please select an option.", "Warning", JOptionPane.WARNING_MESSAGE);
            return;
        }

        String correctAnswer = questions[currentQuestion][5];
        if (selectedOption.equals(correctAnswer)) {
            score++;
        }

        currentQuestion++;
        loadQuestion();
    }

    private void showResult() {
        JOptionPane.showMessageDialog(frame, "You scored " + score + " out of " + questions.length, "Quiz Result", JOptionPane.INFORMATION_MESSAGE);
        frame.dispose();  // Close the application after showing the result
    }
}