Powered by https://www.blackbox.ai: The provided Java code for a quiz application is mostly correct, but there are a few minor issues th

import_java.util.ArrayList; import_java.util.Collections; import_java.util.List;.md

Question:

import java.util.ArrayList; import java.util.Collections; import java.util.List; import java.util.Scanner;

/**

• Main class to launch the Java Quiz application */ public class Main { public static void main(String[] args) { System.out.println("Starting Java Quiz Application..."); JavaQuiz quiz = new JavaQuiz(); quiz.initializeQuestions(); quiz.startQuiz(); } }

/**

• JavaQuiz - A console-based quiz application with Java language questions */ class JavaQuiz { static final Scanner scanner = new Scanner(System.in); int score = 0; int totalQuestions = 0; List questionBank = new ArrayList<>();

  /**

  • Initialize the quiz with Java programming questions */ void initializeQuestions() { // Question 1 questionBank.add(new Question( "What is the correct way to declare a constant in Java?", new String[] { "A) constant int MAX_VALUE = 100;", "B) final int MAX_VALUE = 100;", "C) static MAX_VALUE = 100;", "D) const int MAX_VALUE = 100;" }, 1)); // B is correct

    // Question 2 questionBank.add(new Question( "Which of the following is not a primitive data type in Java?", new String[] { "A) int", "B) float", "C) String", "D) boolean" }, 2)); // C is correct

    // Question 3 questionBank.add(new Question( "What keyword is used to inherit a class in Java?", new String[] { "A) implements", "B) inherits", "C) extends", "D) super" }, 2)); // C is correct

    // Question 4 questionBank.add(new Question( "Which statement is used to exit a loop in Java?", new String[] { "A) exit;", "B) break;", "C) continue;", "D) return;" }, 1)); // B is correct

    // Question 5 questionBank.add(new Question( "What is the output of the following code?\nint x = 5;\nSystem.out.println(x++ + ++x);", new String[] { "A) 10", "B) 11", "C) 12", "D) 13" }, 2)); // C is correct (5 + 7 = 12)

    // Question 6 questionBank.add(new Question( "Which collection class in Java allows duplicate elements?", new String[] { "A) HashSet", "B) TreeSet", "C) ArrayList", "D) HashMap" }, 2)); // C is correct

    // Question 7 questionBank.add(new Question( "What is the access modifier with the most restrictive access in Java?", new String[] { "A) public", "B) protected", "C) default (no modifier)", "D) private" }, 3)); // D is correct

    // Question 8 questionBank.add(new Question( "Which of these keywords is used to define an interface in Java?", new String[] { "A) class", "B) interface", "C) implement", "D) abstract" }, 1)); // B is correct

    // Question 9 questionBank.add(new Question( "What happens when you try to compile and run this code?\npublic class Test {\n public static void main(String[] args) {\n int[] arr = new int[5];\n System.out.println(arr[5]);\n }\n}", new String[] { "A) Compiles and runs without any error", "B) Compiler error", "C) Runtime exception: ArrayIndexOutOfBoundsException", "D) Runtime exception: NullPointerException" }, 2)); // C is correct

    // Question 10 questionBank.add(new Question( "Which statement correctly creates a multi-dimensional array in Java?", new String[] { "A) int[2][3] array = new int[];", "B) int array[2][3] = new int;", "C) int array[][] = new int[2,3];", "D) int[][] array = new int[2][3];" }, 3)); // D is correct

    totalQuestions = questionBank.size(); }

  /**

  • Start the quiz and manage the flow */ void startQuiz() { displayWelcomeMessage();

    // Shuffle questions for randomized order Collections.shuffle(questionBank);

    // Present each question for (int i = 0; i < questionBank.size(); i++) { System.out.println("\nQuestion " + (i + 1) + " of " + totalQuestions); boolean correct = presentQuestion(questionBank.get(i));

     if (correct) {
         System.out.println("Correct! Well done.");
         score++;
     } else {
         System.out.println("Sorry, that's incorrect.");
     }
     
     // Wait for user to press Enter before next question
     System.out.println("\nPress Enter to continue...");
     scanner.nextLine();
    

    }

    // Display final results displayResults(); }

  /**

  • Display welcome message and instructions */ private void displayWelcomeMessage() { System.out.println("========================================"); System.out.println(" WELCOME TO THE JAVA PROGRAMMING QUIZ "); System.out.println("========================================"); System.out.println("Answer the following " + totalQuestions + " questions about Java."); System.out.println("Select your answer by entering A, B, C, or D."); System.out.println("Press Enter to start the quiz..."); scanner.nextLine(); }

  /**

  • Present a question to the user and check their answer

  • @param question The question to present

  • @return true if answered correctly, false otherwise */ private boolean presentQuestion(Question question) { System.out.println("\n" + question.getQuestionText());

    // Display options String[] options = question.getOptions(); for (String option : options) { System.out.println(option); }

    // Get user's answer System.out.print("\nYour answer (A, B, C, or D): "); String userInput = scanner.nextLine().trim().toUpperCase();

    // Convert input to index (0-3) int userAnswer = -1; switch (userInput) { case "A": userAnswer = 0; break; case "B": userAnswer = 1; break; case "C": userAnswer = 2; break; case "D": userAnswer = 3; break; }

    // Check if the answer is correct return userAnswer == question.getCorrectAnswerIndex(); }

  /**

  • Display the final quiz results */ private void displayResults() { System.out.println("\n========================================"); System.out.println(" QUIZ COMPLETED "); System.out.println("========================================"); System.out.println("Your score: " + score + " out of " + totalQuestions);

    // Calculate percentage double percentage = (double) score / totalQuestions * 100; System.out.printf("Percentage: %.1f%%\n", percentage);

    // Display a message based on score if (percentage >= 90) { System.out.println("Excellent! You're a Java expert!"); } else if (percentage >= 70) { System.out.println("Good job! You know Java well."); } else if (percentage >= 50) { System.out.println("Not bad, but you might want to study more Java concepts."); } else { System.out.println("You should spend more time learning Java fundamentals."); }

    System.out.println("\nThank you for taking the Java Quiz!"); } }

/**

• Class representing a quiz question */ class Question { private String questionText; private String[] options; private int correctAnswerIndex;

  /**

  • Constructor for a Question
  • @param questionText The text of the question
  • @param options Array of answer options
  • @param correctAnswerIndex Index of the correct answer (0-based) */ public Question(String questionText, String[] options, int correctAnswerIndex) { this.questionText = questionText; this.options = options; this.correctAnswerIndex = correctAnswerIndex; }

  /**

  • Get the question text
  • @return The question text */ public String getQuestionText() { return questionText; }

  /**

  • Get the answer options
  • @return Array of answer options */ public String[] getOptions() { return options; }

  /**

  • Get the index of the correct answer
  • @return The correct answer index */ public int getCorrectAnswerIndex() { return correctAnswerIndex; } } file name is Main.java correct it

Answer:

The provided Java code for a quiz application is mostly correct, but there are a few minor issues that can be improved for clarity and correctness. Below is the corrected version of the code, along with some comments on the changes made:

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

/**
 * Main class to launch the Java Quiz application
 */
public class Main {
    public static void main(String[] args) {
        System.out.println("Starting Java Quiz Application...");
        JavaQuiz quiz = new JavaQuiz();
        quiz.initializeQuestions();
        quiz.startQuiz();
    }
}

/**
 * JavaQuiz - A console-based quiz application with Java language questions
 */
class JavaQuiz {
    static final Scanner scanner = new Scanner(System.in);
    int score = 0;
    int totalQuestions = 0;
    List<Question> questionBank = new ArrayList<>();

    /**
     * Initialize the quiz with Java programming questions
     */
    void initializeQuestions() {
        // Question 1
        questionBank.add(new Question(
                "What is the correct way to declare a constant in Java?",
                new String[]{
                        "A) constant int MAX_VALUE = 100;",
                        "B) final int MAX_VALUE = 100;",
                        "C) static MAX_VALUE = 100;",
                        "D) const int MAX_VALUE = 100;"
                },
                1)); // B is correct

        // Question 2
        questionBank.add(new Question(
                "Which of the following is not a primitive data type in Java?",
                new String[]{
                        "A) int",
                        "B) float",
                        "C) String",
                        "D) boolean"
                },
                2)); // C is correct

        // Question 3
        questionBank.add(new Question(
                "What keyword is used to inherit a class in Java?",
                new String[]{
                        "A) implements",
                        "B) inherits",
                        "C) extends",
                        "D) super"
                },
                2)); // C is correct

        // Question 4
        questionBank.add(new Question(
                "Which statement is used to exit a loop in Java?",
                new String[]{
                        "A) exit;",
                        "B) break;",
                        "C) continue;",
                        "D) return;"
                },
                1)); // B is correct

        // Question 5
        questionBank.add(new Question(
                "What is the output of the following code?\nint x = 5;\nSystem.out.println(x++ + ++x);",
                new String[]{
                        "A) 10",
                        "B) 11",
                        "C) 12",
                        "D) 13"
                },
                2)); // C is correct (5 + 7 = 12)

        // Question 6
        questionBank.add(new Question(
                "Which collection class in Java allows duplicate elements?",
                new String[]{
                        "A) HashSet",
                        "B) TreeSet",
                        "C) ArrayList",
                        "D) HashMap"
                },
                2)); // C is correct

        // Question 7
        questionBank.add(new Question(
                "What is the access modifier with the most restrictive access in Java?",
                new String[]{
                        "A) public",
                        "B) protected",
                        "C) default (no modifier)",
                        "D) private"
                },
                3)); // D is correct

        // Question 8
        questionBank.add(new Question(
                "Which of these keywords is used to define an interface in Java?",
                new String[]{
                        "A) class",
                        "B) interface",
                        "C) implement",
                        "D) abstract"
                },
                1)); // B is correct

        // Question 9
        questionBank.add(new Question(
                "What happens when you try to compile and run this code?\npublic class Test {\n    public static void main(String[] args) {\n        int[] arr = new int[5];\n        System.out.println(arr[5]);\n    }\n}",
                new String[]{
                        "A) Compiles and runs without any error",
                        "B) Compiler error",
                        "C) Runtime exception: ArrayIndexOutOfBoundsException",
                        "D) Runtime exception: NullPointerException"
                },
                2)); // C is correct

        // Question 10
        questionBank.add(new Question(
                "Which statement correctly creates a multi-dimensional array in Java?",
                new String[]{
                        "A) int[2][3] array = new int[];",
                        "B) int array[2][3] = new int;",
                        "C) int array[][] = new int[2,3];",
                        "D) int[][] array = new int[2][3];"
                },
                3)); // D is correct

        totalQuestions



__Question__:

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

/**
 * Main class to launch the Java Quiz application
 */
public class Main {
    public static void main(String[] args) {
        System.out.println("Starting Java Quiz Application...");
        JavaQuiz quiz = new JavaQuiz();
        quiz.initializeQuestions();
        quiz.startQuiz();
    }
}

/**
 * JavaQuiz - A console-based quiz application with Java language questions
 */
class JavaQuiz {
    static final Scanner scanner = new Scanner(System.in);
    int score = 0;
    int totalQuestions = 0;
    List<Question> questionBank = new ArrayList<>();

    /**
     * Initialize the quiz with Java programming questions
     */
    void initializeQuestions() {
        // Question 1
        questionBank.add(new Question(
                "What is the correct way to declare a constant in Java?",
                new String[]{
                        "A) constant int MAX_VALUE = 100;",
                        "B) final int MAX_VALUE = 100;",
                        "C) static MAX_VALUE = 100;",
                        "D) const int MAX_VALUE = 100;"
                },
                1)); // B is correct

        // Question 2
        questionBank.add(new Question(
                "Which of the following is not a primitive data type in Java?",
                new String[]{
                        "A) int",
                        "B) float",
                        "C) String",
                        "D) boolean"
                },
                2)); // C is correct

        // Question 3
        questionBank.add(new Question(
                "What keyword is used to inherit a class in Java?",
                new String[]{
                        "A) implements",
                        "B) inherits",
                        "C) extends",
                        "D) super"
                },
                2)); // C is correct

        // Question 4
        questionBank.add(new Question(
                "Which statement is used to exit a loop in Java?",
                new String[]{
                        "A) exit;",
                        "B) break;",
                        "C) continue;",
                        "D) return;"
                },
                1)); // B is correct

        // Question 5
        questionBank.add(new Question(
                "What is the output of the following code?\nint x = 5;\nSystem.out.println(x++ + ++x);",
                new String[]{
                        "A) 10",
                        "B) 11",
                        "C) 12",
                        "D) 13"
                },
                2)); // C is correct (5 + 7 = 12)

        // Question 6
        questionBank.add(new Question(
                "Which collection class in Java allows duplicate elements?",
                new String[]{
                        "A) HashSet",
                        "B) TreeSet",
                        "C) ArrayList",
                        "D) HashMap"
                },
                2)); // C is correct

        // Question 7
        questionBank.add(new Question(
                "What is the access modifier with the most restrictive access in Java?",
                new String[]{
                        "A) public",
                        "B) protected",
                        "C) default (no modifier)",
                        "D) private"
                },
                3)); // D is correct

        // Question 8
        questionBank.add(new Question(
                "Which of these keywords is used to define an interface in Java?",
                new String[]{
                        "A) class",
                        "B) interface",
                        "C) implement",
                        "D) abstract"
                },
                1)); // B is correct

        // Question 9
        questionBank.add(new Question(
                "What happens when you try to compile and run this code?\npublic class Test {\n    public static void main(String[] args) {\n        int[] arr = new int[5];\n        System.out.println(arr[5]);\n    }\n}",
                new String[]{
                        "A) Compiles and runs without any error",
                        "B) Compiler error",
                        "C) Runtime exception: ArrayIndexOutOfBoundsException",
                        "D) Runtime exception: NullPointerException"
                },
                2)); // C is correct

        // Question 10
        questionBank.add(new Question(
                "Which statement correctly creates a multi-dimensional array in Java?",
                new String[]{
                        "A) int[2][3] array = new int[];",
                        "B) int array[2][3] = new int;",
                        "C) int array[][] = new int[2,3];",
                        "D) int[][] array = new int[2][3];"
                },
                3)); // D is correct

        

        totalQuestions = questionBank.size();
    }

    /**
     * Start the quiz and manage the flow
     */
     void startQuiz() {
        displayWelcomeMessage();
        
        // Shuffle questions for randomized order
        Collections.shuffle(questionBank);
        
        // Present each question
        for (int i = 0; i < questionBank.size(); i++) {
            System.out.println("\nQuestion " + (i + 1) + " of " + totalQuestions);
            boolean correct = presentQuestion(questionBank.get(i));
            
            if (correct) {
                System.out.println("Correct! Well done.");
                score++;
            } else {
                System.out.println("Sorry, that's incorrect.");
            }
            
            // Wait for user to press Enter before next question
            System.out.println("\nPress Enter to continue...");
            scanner.nextLine();
        }
        
        // Display final results
        displayResults();
    }
    
    /**
     * Display welcome message and instructions
     */
    private void displayWelcomeMessage() {
        System.out.println("========================================");
        System.out.println("  WELCOME TO THE JAVA PROGRAMMING QUIZ  ");
        System.out.println("========================================");
        System.out.println("Answer the following " + totalQuestions + " questions about Java.");
        System.out.println("Select your answer by entering A, B, C, or D.");
        System.out.println("Press Enter to start the quiz...");
        scanner.nextLine();
    }
    
    /**
     * Present a question to the user and check their answer
     * @param question The question to present
     * @return true if answered correctly, false otherwise
     */
    private boolean presentQuestion(Question question) {
        System.out.println("\n" + question.getQuestionText());
        
        // Display options
        String[] options = question.getOptions();
        for (String option : options) {
            System.out.println(option);
        }
        
        // Get user's answer
        System.out.print("\nYour answer (A, B, C, or D): ");
        String userInput = scanner.nextLine().trim().toUpperCase();
        
        // Convert input to index (0-3)
        int userAnswer = -1;
        switch (userInput) {
            case "A": userAnswer = 0; break;
            case "B": userAnswer = 1; break;
            case "C": userAnswer = 2; break;
            case "D": userAnswer = 3; break;
        }
        
        // Check if the answer is correct
        return userAnswer == question.getCorrectAnswerIndex();
    }
    
    /**
     * Display the final quiz results
     */
    private void displayResults() {
        System.out.println("\n========================================");
        System.out.println("            QUIZ COMPLETED              ");
        System.out.println("========================================");
        System.out.println("Your score: " + score + " out of " + totalQuestions);
        
        // Calculate percentage
        double percentage = (double) score / totalQuestions * 100;
        System.out.printf("Percentage: %.1f%%\n", percentage);
        
        // Display a message based on score
        if (percentage >= 90) {
            System.out.println("Excellent! You're a Java expert!");
        } else if (percentage >= 70) {
            System.out.println("Good job! You know Java well.");
        } else if (percentage >= 50) {
            System.out.println("Not bad, but you might want to study more Java concepts.");
        } else {
            System.out.println("You should spend more time learning Java fundamentals.");
        }
        
        System.out.println("\nThank you for taking the Java Quiz!");
    }
}

/**
 * Class representing a quiz question
 */
class Question {
    private String questionText;
    private String[] options;
    private int correctAnswerIndex;
    
    /**
     * Constructor for a Question
     * @param questionText The text of the question
     * @param options Array of answer options
     * @param correctAnswerIndex Index of the correct answer (0-based)
     */
    public Question(String questionText, String[] options, int correctAnswerIndex) {
        this.questionText = questionText;
        this.options = options;
        this.correctAnswerIndex = correctAnswerIndex;
    }
    
    /**
     * Get the question text
     * @return The question text
     */
    public String getQuestionText() {
        return questionText;
    }
    
    /**
     * Get the answer options
     * @return Array of answer options
     */
    public String[] getOptions() {
        return options;
    }
    
    /**
     * Get the index of the correct answer
     * @return The correct answer index
     */
    public int getCorrectAnswerIndex() {
        return correctAnswerIndex;
    }
} make a web based quiz using the code 



__Answer__:

To convert the Java console-based quiz application into a web-based quiz application, we can use Java with a web framework like Spring Boot. Below is a simplified version of how you can implement a web-based quiz application using Spring Boot, Thymeleaf for the front-end, and the same quiz logic.

### Step 1: Set Up Spring Boot Project

1. **Create a new Spring Boot project** using Spring Initializr (https://start.spring.io/).
   - Choose dependencies: Spring Web, Thymeleaf, Spring Boot DevTools.

2. **Project Structure**:

src ├── main │ ├── java │ │ └── com │ │ └── example │ │ └── quiz │ │ ├── QuizApplication.java │ │ ├── controller │ │ │ └── QuizController.java │ │ ├── model │ │ │ └── Question.java │ │ └── service │ │ └── QuizService.java │ └── resources │ ├── templates │ │ ├── quiz.html │ │ └── result.html │ └── application.properties

### Step 2: Create the Application Class

```java
// QuizApplication.java
package com.example.quiz;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class QuizApplication {
 public static void main(String[] args) {
     SpringApplication.run(QuizApplication.class, args);
 }
}

Step 3: Create the Question Model

// Question.java
package com.example.quiz.model;

public class Question {
    private String questionText;
    private String[] options;
    private int correctAnswerIndex;

    public Question(String questionText, String[] options, int correctAnswerIndex) {
        this.questionText = questionText;
        this.options = options;
        this.correctAnswerIndex = correctAnswerIndex;
    }

    public String getQuestionText() {
        return questionText;
    }

    public String[] getOptions() {
        return options;
    }

    public int getCorrectAnswerIndex() {
        return correctAnswerIndex;
    }
}

Step 4: Create the Quiz Service

// QuizService.java
package com.example.quiz.service;

import com.example.quiz.model.Question;
import org.springframework.stereotype.Service;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

@Service
public class QuizService {
    private List<Question> questionBank = new ArrayList<>();

    public QuizService() {
        initializeQuestions();
    }

    private void initializeQuestions() {
        questionBank.add(new Question("What is the correct way to declare a constant in Java?",
                new String[]{"A) constant int MAX_VALUE = 100;", "B) final int MAX_VALUE = 100;", "C) static MAX_VALUE = 100;", "D) const int MAX_VALUE = 100;"}, 1));
        questionBank.add(new Question("Which of the following is not a primitive data type in Java?",
                new String[]{"A) int", "B) float", "C) String", "D) boolean"}, 2));
        // Add more questions as needed...
    }

    public List<Question> getQuestions() {
        Collections.shuffle(questionBank);
        return questionBank;
    }
}

Step 5: Create the Quiz Controller

// QuizController.java
package com.example.quiz.controller;

import com.example.quiz.model.Question;
import com.example.quiz.service.QuizService;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;

import java.util.List;

@Controller
public class QuizController {
    private final QuizService quizService;

    public QuizController(QuizService quizService) {
        this.quizService = quizService;
    }

    @GetMapping("/quiz")
    public String showQuiz(Model model) {
        List<Question> questions = quizService.getQuestions();
        model.addAttribute("questions", questions);
        return "quiz";
    }

    @PostMapping("/result")
    public String showResult(@RequestParam List<Integer> answers, Model model) {
        List<Question> questions = quizService.getQuestions();
        int score = 0;

        for (int i = 0; i < questions.size(); i++) {
            if (answers.get(i) == questions.get(i).getCorrectAnswerIndex()) {
                score++;
            }
        }

        model.addAttribute("score", score);
        model.addAttribute("total", questions.size());
        return "result";
    }
}




__Question__:

without springboot



__Answer__:


The user wants to convert their Java console quiz program into a web-based quiz, but explicitly without using Spring Boot or any advanced backend framework.

Given this, the best approach is to create a pure frontend implementation using HTML, CSS, and JavaScript that replicates the quiz functionality.

Since Java does not run in the browser and using backend Java frameworks was excluded, the best is to rewrite the quiz as a web page with inline HTML, CSS, and JS that can be opened directly in a browser.

Plan:
- Create a single HTML file with the quiz questions (same questions as in Java code).
- Display one question at a time with options "A", "B", "C", "D".
- Allow user to select an option and submit, then show if it was correct or not.
- After all questions, show final score and percentage with messages.
- Use pure JavaScript to manage the quiz flow (shuffling questions, scoring, navigation).
- Include all questions and answers as in the Java code, preserving correctness.

Dependent files: none besides the single HTML file.

Followup: user can open the HTML file in any modern browser to run the quiz.

I will now prepare the complete HTML file with inline CSS and JS for the quiz.


`java_quiz.html`
```html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>Java Programming Quiz</title>
<style>
    body {
        font-family: Arial, sans-serif;
        background-color: #f4f7f9;
        margin: 0; padding: 0;
        display: flex;
        justify-content: center;
        align-items: flex-start;
        min-height: 100vh;
        padding: 20px;
    }
    #quiz-container {
        background: white;
        border-radius: 8px;
        max-width: 600px;
        width: 100%;
        box-shadow: 0 0 10px rgba(0,0,0,0.1);
        padding: 30px;
        box-sizing: border-box;
    }
    h1 {
        text-align: center;
        color: #0a589e;
        margin-bottom: 15px;
    }
    .question-number {
        font-weight: bold;
        margin-bottom: 10px;
    }
    .question-text {
        font-size: 1.2em;
        margin-bottom: 15px;
        white-space: pre-line;
    }
    .options {
        list-style-type: none;
        padding: 0;
        margin-bottom: 20px;
    }
    .options li {
        margin-bottom: 10px;
    }
    .option-label {
        cursor: pointer;
        display: flex;
        align-items: center;
        padding: 10px;
        background-color: #e9f0f8;
        border-radius: 6px;
        transition: background-color 0.2s ease;
        user-select: none;
    }
    input[type="radio"] {
        margin-right: 12px;
        cursor: pointer;
    }
    .option-label:hover {
        background-color: #c7d9f1;
    }
    #submit-btn, #next-btn, #restart-btn {
        padding: 12px 25px;
        font-size: 1em;
        border: none;
        border-radius: 6px;
        color: white;
        background-color: #0a589e;
        cursor: pointer;
        transition: background-color 0.3s ease;
    }
    #submit-btn:disabled {
        background-color: #7a9fc9;
        cursor: default;
    }
    #submit-btn:hover:not(:disabled),
    #next-btn:hover,
    #restart-btn:hover {
        background-color: #074073;
    }
    #feedback {
        font-weight: bold;
        margin-bottom: 20px;
    }
    #final-results {
        text-align: center;
    }
    #final-results h2 {
        color: #0a589e;
        margin-bottom: 10px;
    }
    #final-results p {
        font-size: 1.1em;
        margin: 5px 0;
    }
</style>
</head>
<body>
<div id="quiz-container">
    <h1>Java Programming Quiz</h1>
    <div id="quiz-content">
        <div class="question-number" id="question-number"></div>
        <div class="question-text" id="question-text"></div>
        <ul class="options" id="options-list"></ul>
        <button id="submit-btn" disabled>Submit Answer</button>
        <button id="next-btn" style="display:none;">Next Question</button>
        <div id="feedback"></div>
    </div>
    <div id="final-results" style="display:none;">
        <h2>Quiz Completed!</h2>
        <p id="score-text"></p>
        <p id="percentage-text"></p>
        <p id="message-text"></p>
        <button id="restart-btn">Restart Quiz</button>
    </div>
</div>
<script>
    // Questions data (copied from Java code, indexes zero-based for correctAnswer)
    const questions = [
        {
            question: "What is the correct way to declare a constant in Java?",
            options: [
                "A) constant int MAX_VALUE = 100;",
                "B) final int MAX_VALUE = 100;",
                "C) static MAX_VALUE = 100;",
                "D) const int MAX_VALUE = 100;"
            ],
            correctAnswerIndex: 1
        },
        {
            question: "Which of the following is not a primitive data type in Java?",
            options: [
                "A) int",
                "B) float",
                "C) String",
                "D) boolean"
            ],
            correctAnswerIndex: 2
        },
        {
            question: "What keyword is used to inherit a class in Java?",
            options: [
                "A) implements",
                "B) inherits",
                "C) extends",
                "D) super"
            ],
            correctAnswerIndex: 2
        },
        {
            question: "Which statement is used to exit a loop in Java?",
            options: [
                "A) exit;",
                "B) break;",
                "C) continue;",
                "D) return;"
            ],
            correctAnswerIndex: 1
        },
        {
            question: "What is the output of the following code?\nint x = 5;\nSystem.out.println(x++ + ++x);",
            options: [
                "A) 10",
                "B) 11",
                "C) 12",
                "D) 13"
            ],
            correctAnswerIndex: 2
        },
        {
            question: "Which collection class in Java allows duplicate elements?",
            options: [
                "A) HashSet",
                "B) TreeSet",
                "C) ArrayList",
                "D) HashMap"
            ],
            correctAnswerIndex: 2
        },
        {
            question: "What is the access modifier with the most restrictive access in Java?",
            options: [
                "A) public",
                "B) protected",
                "C) default (no modifier)",
                "D) private"
            ],
            correctAnswerIndex: 3
        },
        {
            question: "Which of these keywords is used to define an interface in Java?",
            options: [
                "A) class",
                "B) interface",
                "C) implement",
                "D) abstract"
            ],
            correctAnswerIndex: 1
        },
        {
            question: "What happens when you try to compile and run this code?\npublic class Test {\n    public static void main(String[] args) {\n        int[] arr = new int[5];\n        System.out.println(arr[5]);\n    }\n}",
            options: [
                "A) Compiles and runs without any error",
                "B) Compiler error",
                "C) Runtime exception: ArrayIndexOutOfBoundsException",
                "D) Runtime exception: NullPointerException"
            ],
            correctAnswerIndex: 2
        },
        {
            question: "Which statement correctly creates a multi-dimensional array in Java?",
            options: [
                "A) int[2][3] array = new int[];",
                "B) int array[2][3] = new int;",
                "C) int array[][] = new int[2,3];",
                "D) int[][] array = new int[2][3];"
            ],
            correctAnswerIndex: 3
        }
    ];

    // Shuffle questions function (Fisher-Yates)
    function shuffleArray(array) {
        for (let i = array.length - 1; i > 0; i--) {
            const j = Math.floor(Math.random() * (i + 1));
            [array[i], array[j]] = [array[j], array[i]];
        }
    }

    // Quiz state
    let shuffledQuestions = [];
    let currentQuestionIndex = 0;
    let score = 0;
    let userAnswers = [];

    // DOM Elements
    const questionNumberEl = document.getElementById('question-number');
    const questionTextEl = document.getElementById('question-text');
    const optionsListEl = document.getElementById('options-list');
    const submitBtn = document.getElementById('submit-btn');
    const nextBtn = document.getElementById('next-btn');
    const feedbackEl = document.getElementById('feedback');
    const quizContentEl = document.getElementById('quiz-content');
    const finalResultsEl = document.getElementById('final-results');
    const scoreTextEl = document.getElementById('score-text');
    const percentageTextEl = document.getElementById('percentage-text');
    const messageTextEl = document.getElementById('message-text');
    const restartBtn = document.getElementById('restart-btn');

    // Initialize quiz
    function initQuiz() {
        shuffledQuestions = [...questions];
        shuffleArray(shuffledQuestions);
        currentQuestionIndex = 0;
        score = 0;
        userAnswers = [];
        finalResultsEl.style.display = 'none';
        quizContentEl.style.display = 'block';
        feedbackEl.textContent = '';
        nextBtn.style.display = 'none';
        submitBtn.style.display = 'inline-block';
        submitBtn.disabled = true;
        displayQuestion();
    }

    // Display current question
    function displayQuestion() {
        const q = shuffledQuestions[currentQuestionIndex];
        questionNumberEl.textContent = \`Question \${currentQuestionIndex + 1} of \${shuffledQuestions.length}\`;
        questionTextEl.textContent = q.question;
        optionsListEl.innerHTML = '';

        q.options.forEach((option, index) => {
            const li = document.createElement('li');
            const label = document.createElement('label');
            label.classList.add('option-label');
            const radio = document.createElement('input');
            radio.type = 'radio';
            radio.name = 'option';
            radio.value = index;
            radio.addEventListener('change', () => {
                submitBtn.disabled = false;
                feedbackEl.textContent = '';
            });
            label.appendChild(radio);
            label.appendChild(document.createTextNode(option));
            li.appendChild(label);
            optionsListEl.appendChild(li);
        });
    }

    // Submit answer handler
    submitBtn.addEventListener('click', () => {
        const selectedOption = document.querySelector('input[name="option"]:checked');
        if (!selectedOption) {
            feedbackEl.textContent = 'Please select an answer before submitting.';
            return;
        }
        submitBtn.disabled = true;
        const answerIndex = parseInt(selectedOption.value);
        userAnswers.push(answerIndex);
        const correctIndex = shuffledQuestions[currentQuestionIndex].correctAnswerIndex;

        if (answerIndex === correctIndex) {
            feedbackEl.textContent = 'Correct! Well done.';
            score++;
        } else {
            feedbackEl.textContent = \`Sorry, that\'s incorrect. Correct answer is: \${shuffledQuestions[currentQuestionIndex].options[correctIndex]}\`;
        }

        submitBtn.style.display = 'none';
        nextBtn.style.display = currentQuestionIndex + 1 < shuffledQuestions.length ? 'inline-block' : 'none';

        if (currentQuestionIndex + 1 === shuffledQuestions.length) {
            // Prepare to show final results in next button click
            nextBtn.textContent = 'See Results';
        }
    });

    // Next question handler
    nextBtn.addEventListener('click', () => {
        currentQuestionIndex++;
        if (currentQuestionIndex < shuffledQuestions.length) {
            displayQuestion();
            feedbackEl.textContent = '';
            submitBtn.style.display = 'inline-block';
            submitBtn.disabled = true;
            nextBtn.style.display = 'none';
        } else {
            showResults();
        }
    });

    // Show final results
    function showResults() {
        quizContentEl.style.display = 'none';
        finalResultsEl.style.display = 'block';

        scoreTextEl.textContent = \`Your score: \${score} out of \${shuffledQuestions.length}\`;
        const percentage = (score / shuffledQuestions.length) * 100;
        percentageTextEl.textContent = \`Percentage: \${percentage.toFixed(1)}%\`;

        let message = '';
        if (percentage >= 90) {
            message = "Excellent! You're a Java expert!";
        } else if (percentage >= 70) {
            message = "Good job! You know Java well.";
        } else if (percentage >= 50) {
            message = "Not bad, but you might want to study more Java concepts.";
        } else {
            message = "You should spend more time learning Java fundamentals.";
        }
        messageTextEl.textContent = message;
    }

    // Restart quiz handler
    restartBtn.addEventListener('click', () => {
        initQuiz();
        nextBtn.textContent = 'Next Question';
    });

    // Start quiz on load
    window.onload = () => {
        initQuiz();
    };
</script>
</body>
</html>

Question:

use java also

Answer:

The user is requesting a web-based quiz using Java as well as the frontend. They previously rejected Spring Boot or similar frameworks, so we cannot use typical Java backend frameworks.

However, to run Java code in a web environment, options are limited without server backend - either we use servlets/JSP or a standalone Java server, but these require a server environment and build setup.

Given the constraints, the only way to use Java as well as a web interface without Spring Boot is to create a simple Java HTTP server (using built-in Java HTTP server or servlets) that serves a web page and handles quiz logic on the backend.

We can do a minimal Java HTTP server that serves the quiz page (HTML+JS) and receives user answers via POST, then responds with the next question or final scores. This will be a simple backend + frontend web app with Java.

Plan:

• Create a Java class implementing a simple HTTP server using com.sun.net.httpserver.HttpServer from the standard Java DevKit.
• Serve the quiz page (HTML+JS) on path "/" via GET.
• The frontend can be mostly static or can fetch questions from the server.
• The server will store questions and current user state (possibly in-memory keyed by session or simple cookie).
• For simplicity, we can keep all state on the client and just return answers to validate via POST API to the Java server.

We will create:

• A single Java file Main.java that starts the HTTP server,
• Serves a static HTML quiz page,
• Exposes an API endpoint to validate answers and return the next question and results.

This approach meets the user's request to use Java with a web interface without Spring Boot.

I will proceed with a minimal example implementing these.

Main.java

import com.sun.net.httpserver.Headers;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;

import java.io.*;
import java.net.InetSocketAddress;
import java.nio.charset.StandardCharsets;
import java.util.*;
import java.util.concurrent.Executors;

/**
 * A simple Java HTTP server serving a web-based Java quiz application.
 * Serves static quiz page on "/" and handles quiz API on "/api".
 */
public class Main {
    static class Question {
        String questionText;
        String[] options;
        int correctAnswerIndex;

        Question(String questionText, String[] options, int correctAnswerIndex) {
            this.questionText = questionText;
            this.options = options;
            this.correctAnswerIndex = correctAnswerIndex;
        }
    }

    static List<Question> questionBank = new ArrayList<>();

    // Initialize questions - same as original Java quiz
    static void initializeQuestions() {
        questionBank.add(new Question(
                "What is the correct way to declare a constant in Java?",
                new String[]{
                        "A) constant int MAX_VALUE = 100;",
                        "B) final int MAX_VALUE = 100;",
                        "C) static MAX_VALUE = 100;",
                        "D) const int MAX_VALUE = 100;"
                },
                1));
        questionBank.add(new Question(
                "Which of the following is not a primitive data type in Java?",
                new String[]{
                        "A) int",
                        "B) float",
                        "C) String",
                        "D) boolean"
                },
                2));
        questionBank.add(new Question(
                "What keyword is used to inherit a class in Java?",
                new String[]{
                        "A) implements",
                        "B) inherits",
                        "C) extends",
                        "D) super"
                },
                2));
        questionBank.add(new Question(
                "Which statement is used to exit a loop in Java?",
                new String[]{
                        "A) exit;",
                        "B) break;",
                        "C) continue;",
                        "D) return;"
                },
                1));
        questionBank.add(new Question(
                "What is the output of the following code?\\nint x = 5;\\nSystem.out.println(x++ + ++x);",
                new String[]{
                        "A) 10",
                        "B) 11",
                        "C) 12",
                        "D) 13"
                },
                2));
        questionBank.add(new Question(
                "Which collection class in Java allows duplicate elements?",
                new String[]{
                        "A) HashSet",
                        "B) TreeSet",
                        "C) ArrayList",
                        "D) HashMap"
                },
                2));
        questionBank.add(new Question(
                "What is the access modifier with the most restrictive access in Java?",
                new String[]{
                        "A) public",
                        "B) protected",
                        "C) default (no modifier)",
                        "D) private"
                },
                3));
        questionBank.add(new Question(
                "Which of these keywords is used to define an interface in Java?",
                new String[]{
                        "A) class",
                        "B) interface",
                        "C) implement",
                        "D) abstract"
                },
                1));
        questionBank.add(new Question(
                "What happens when you try to compile and run this code?\\npublic class Test {\\n    public static void main(String[] args) {\\n        int[] arr = new int[5];\\n        System.out.println(arr[5]);\\n    }\\n}",
                new String[]{
                        "A) Compiles and runs without any error",
                        "B) Compiler error",
                        "C) Runtime exception: ArrayIndexOutOfBoundsException",
                        "D) Runtime exception: NullPointerException"
                },
                2));
        questionBank.add(new Question(
                "Which statement correctly creates a multi-dimensional array in Java?",
                new String[]{
                        "A) int[2][3] array = new int[];",
                        "B) int array[2][3] = new int;",
                        "C) int array[][] = new int[2,3];",
                        "D) int[][] array = new int[2][3];"
                },
                3));
    }

    // Simple helper: convert question list to JSON string manually (since no library)
    static String questionToJson(Question q) {
        StringBuilder sb = new StringBuilder();
        sb.append("{");
        sb.append("\"questionText\":").append("\"").append(escapeJson(q.questionText)).append("\",");
        sb.append("\"options\":[");
        for (int i = 0; i < q.options.length; i++) {
            sb.append("\"").append(escapeJson(q.options[i])).append("\"");
            if (i < q.options.length -1) sb.append(",");
        }
        sb.append("],");
        sb.append("\"correctAnswerIndex\":").append(q.correctAnswerIndex);
        sb.append("}");
        return sb.toString();
    }

    static String escapeJson(String s) {
        return s.replace("\\", "\\\\").replace("\"", "\\\"").replace("\n", "\\n");
    }

    // Serves static quiz HTML + JS frontend
    static class RootHandler implements HttpHandler {
        private final String quizPage;

        RootHandler(String quizPage) {
            this.quizPage = quizPage;
        }

        @Override
        public void handle(HttpExchange exchange) throws IOException {
            if (!exchange.getRequestMethod().equalsIgnoreCase("GET")) {
                sendResponse(exchange, 405, "Method Not Allowed");
                return;
            }

            Headers headers = exchange.getResponseHeaders();
            headers.set("Content-Type", "text/html; charset=UTF-8");
            sendResponse(exchange, 200, quizPage);
        }
    }

    // API handler to respond to quiz requests
    static class ApiHandler implements HttpHandler {
        @Override
        public void handle(HttpExchange exchange) throws IOException {
            String method = exchange.getRequestMethod();
            if (!method.equalsIgnoreCase("POST")) {
                sendResponse(exchange, 405, "Method Not Allowed");
                return;
            }

            // Read body
            InputStream is = exchange.getRequestBody();
            String body = new BufferedReader(new InputStreamReader(is, StandardCharsets.UTF_8))
                    .lines()
                    .reduce("", (acc, line) -> acc + line);

            // Parse body, expecting JSON with "questionIndex" and "userAnswer"
            // Since no JSON library, do simple string parsing
            int questionIndex = -1;
            int userAnswer = -1;

            try {
                Map<String,String> parsed = parseQuery(body);
                questionIndex = Integer.parseInt(parsed.getOrDefault("questionIndex","-1"));
                userAnswer = Integer.parseInt(parsed.getOrDefault("userAnswer","-1"));
            } catch (Exception e) {
                sendResponse(exchange,400,"Invalid request body");
                return;
            }

            if (questionIndex < 0 || questionIndex >= questionBank.size()) {
                sendResponse(exchange,400,"Invalid question index");
                return;
            }

            Question question = questionBank.get(questionIndex);
            boolean isCorrect = (userAnswer == question.correctAnswerIndex);

            // Build response JSON with correct answer and correctness
            StringBuilder responseJson = new StringBuilder();
            responseJson.append("{");
            responseJson.append("\"correct\":").append(isCorrect).append(",");
            responseJson.append("\"correctAnswerIndex\":").append(question.correctAnswerIndex);
            responseJson.append("}");

            Headers headers = exchange.getResponseHeaders();
            headers.set("Content-Type", "application/json; charset=UTF-8");
            sendResponse(exchange, 200, responseJson.toString());
        }
    }

    // Simple parse for application/x-www-form-urlencoded or JSON-like body (assumes key=value&key2=value2)
    static Map<String,String> parseQuery(String query) {
        Map<String,String> map = new HashMap<>();
        String[] pairs = query.split("&");
        for (String pair : pairs) {
            int idx = pair.indexOf('=');
            if (idx > 0 && idx < pair.length()-1) {
                String key = decodeURIComponent(pair.substring(0, idx));
                String val = decodeURIComponent(pair.substring(idx+1));
                map.put(key,val);
            }
        }
        return map;
    }

    static String decodeURIComponent(String s) {
        try {
            return java.net.URLDecoder.decode(s, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            return s;
        }
    }

    static void sendResponse(HttpExchange exchange, int code, String response) throws IOException {
        byte[] bytes = response.getBytes(StandardCharsets.UTF_8);
        exchange.sendResponseHeaders(code, bytes.length);
        OutputStream os = exchange.getResponseBody();
        os.write(bytes);
        os.close();
    }

    public static void main(String[] args) throws IOException {
        initializeQuestions();

        int port = 8000;
        HttpServer server = HttpServer.create(new InetSocketAddress(port), 0);
        System.out.println("Starting server at http://localhost:" + port);

        // Load HTML page content
        String html = getQuizHtml();

        server.createContext("/", new RootHandler(html));
        server.createContext("/api/answer", new ApiHandler());

        server.setExecutor(Executors.newCachedThreadPool());
        server.start();
    }

    // Returns the HTML + JS frontend quiz page as a String
    static String getQuizHtml() {
        // Questions data only on client side for shuffling and display, but answers validated via API
        StringBuilder questionsJsArray = new StringBuilder();
        questionsJsArray.append("[");
        for (int i = 0; i < questionBank.size(); i++) {
            questionsJsArray.append(questionToJson(questionBank.get(i)));
            if (i < questionBank.size() - 1) questionsJsArray.append(",");
        }
        questionsJsArray.append("]");

        String page = """
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>Java Programming Quiz</title>
<style>
    body {
        font-family: Arial, sans-serif;
        background-color: #f4f7f9;
        margin: 0; padding: 0;
        display: flex;
        justify-content: center;
        align-items: flex-start;
        min-height: 100vh;
        padding: 20px;
    }
    #quiz-container {
        background: white;
        border-radius: 8px;
        max-width: 600px;
        width: 100%;
        box-shadow: 0 0 10px rgba(0,0,0,0.1);
        padding: 30px;
        box-sizing: border-box;
    }
    h1 {
        text-align: center;
        color: #0a589e;
        margin-bottom: 15px;
    }
    .question-number {
        font-weight: bold;
        margin-bottom: 10px;
    }
    .question-text {
        font-size: 1.2em;
        margin-bottom: 15px;
        white-space: pre-line;
    }
    .options {
        list-style-type: none;
        padding: 0;
        margin-bottom: 20px;
    }
    .options li {
        margin-bottom: 10px;
    }
    .option-label {
        cursor: pointer;
        display: flex;
        align-items: center;
        padding: 10px;
        background-color: #e9f0f8;
        border-radius: 6px;
        transition: background-color 0.2s ease;
        user-select: none;
    }
    input[type="radio"] {
        margin-right: 12px;
        cursor: pointer;
    }
    .option-label:hover {
        background-color: #c7d9f1;
    }
    #submit-btn, #next-btn, #restart-btn {
        padding: 12px 25px;
        font-size: 1em;
        border: none;
        border-radius: 6px;
        color: white;
        background-color: #0a589e;
        cursor: pointer;
        transition: background-color 0.3s ease;
    }
    #submit-btn:disabled {
        background-color: #7a9fc9;
        cursor: default;
    }
    #submit-btn:hover:not(:disabled),
    #next-btn:hover,
    #restart-btn:hover {
        background-color: #074073;
    }
    #feedback {
        font-weight: bold;
        margin-bottom: 20px;
    }
    #final-results {
        text-align: center;
    }
    #final-results h2 {
        color: #0a589e;
        margin-bottom: 10px;
    }
    #final-results p {
        font-size: 1.1em;
        margin: 5px 0;
    }
</style>
</head>
<body>
<div id="quiz-container">
    <h1>Java Programming Quiz</h1>
    <div id="quiz-content">
        <div class="question-number" id="question-number"></div>
        <div class="question-text" id="question-text"></div>
        <ul class="options" id="options-list"></ul>
        <button id="submit-btn" disabled>Submit Answer</button>
        <button id="next-btn" style="display:none;">Next Question</button>
        <div id="feedback"></div>
    </div>
    <div id="final-results" style="display:none;">
        <h2>Quiz Completed!</h2>
        <p id="score-text"></p>
        <p id="percentage-text"></p>
        <p id="message-text"></p>
        <button id="restart-btn">Restart Quiz</button>
    </div>
</div>
<script>
    // Questions copied from server-side data to client for display/shuffle only
    const questions = """ + questionsJsArray.toString() + """;

    // Shuffle questions function
    function shuffleArray(array) {
        for (let i = array.length - 1; i > 0; i--) {
            const j = Math.floor(Math.random() * (i + 1));
            [array[i], array[j]] = [array[j], array[i]];
        }
    }

    let shuffledQuestions = [];
    let currentQuestionIndex = 0;
    let score = 0;

    // DOM Elements
    const questionNumberEl = document.getElementById('question-number');
    const questionTextEl = document.getElementById('question-text');
    const optionsListEl = document.getElementById('options-list');
    const submitBtn = document.getElementById('submit-btn');
    const nextBtn = document.getElementById('next-btn');
    const feedbackEl = document.getElementById('feedback');
    const quizContentEl = document.getElementById('quiz-content');
    const finalResultsEl = document.getElementById('final-results');
    const scoreTextEl = document.getElementById('score-text');
    const percentageTextEl = document.getElementById('percentage-text');
    const messageTextEl = document.getElementById('message-text');
    const restartBtn = document.getElementById('restart-btn');

    function initQuiz() {
        shuffledQuestions = [...questions];
        shuffleArray(shuffledQuestions);
        currentQuestionIndex = 0;
        score = 0;
        finalResultsEl.style.display = 'none';
        quizContentEl.style.display = 'block';
        feedbackEl.textContent = '';
        nextBtn.style.display = 'none';
        submitBtn.style.display = 'inline-block';
        submitBtn.disabled = true;
        nextBtn.textContent = 'Next Question';
        displayQuestion();
    }

    function displayQuestion() {
        const q = shuffledQuestions[currentQuestionIndex];
        questionNumberEl.textContent = \`Question \${currentQuestionIndex + 1} of \${shuffledQuestions.length}\`;
        questionTextEl.textContent = q.questionText;
        optionsListEl.innerHTML = '';

        q.options.forEach((option, index) => {
            const li = document.createElement('li');
            const label = document.createElement('label');
            label.classList.add('option-label');
            const radio = document.createElement('input');
            radio.type = 'radio';
            radio.name = 'option';
            radio.value = index;
            radio.addEventListener('change', () => {
                submitBtn.disabled = false;
                feedbackEl.textContent = '';
            });
            label.appendChild(radio);
            label.appendChild(document.createTextNode(option));
            li.appendChild(label);
            optionsListEl.appendChild(li);
        });
    }

    // Submit answer, validate with server API
    submitBtn.addEventListener('click', () => {
        const selectedOption = document.querySelector('input[name="option"]:checked');
        if (!selectedOption) {
            feedbackEl.textContent = 'Please select an answer before submitting.';
            return;
        }
        submitBtn.disabled = true;

        const userAnswerIndex = parseInt(selectedOption.value);
        const qIndex = currentQuestionIndex;

        // Prepare data to send as form-urlencoded
        const data = new URLSearchParams();
        data.append('questionIndex', qIndex);
        data.append('userAnswer', userAnswerIndex);

        fetch('/api/answer', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/x-www-form-urlencoded'
            },
            body: data.toString()
        }).then(response => response.json())
          .then(json => {
              if (json.correct) {
                  feedbackEl.textContent = 'Correct! Well done.';
                  score++;
              } else {
                  feedbackEl.textContent = \`Sorry, that\'s incorrect. Correct answer is: \${shuffledQuestions[qIndex].options[json.correctAnswerIndex]}\`;
              }
              submitBtn.style.display = 'none';
              if (currentQuestionIndex + 1 < shuffledQuestions.length) {
                  nextBtn.style.display = 'inline-block';
              } else {
                  nextBtn.style.display = 'inline-block';
                  nextBtn.textContent = 'See Results';
              }
          }).catch(err => {
              feedbackEl.textContent = 'Error validating answer, try again.';
              submitBtn.disabled = false;
          });
    });

    nextBtn.addEventListener('click', () => {
        currentQuestionIndex++;
        if (currentQuestionIndex < shuffledQuestions.length) {
            displayQuestion();
            feedbackEl.textContent = '';
            submitBtn.style.display = 'inline-block';
            submitBtn.disabled = true;
            nextBtn.style.display = 'none';
        } else {
            showResults();
        }
    });

    function showResults() {
        quizContentEl.style.display = 'none';
        finalResultsEl.style.display = 'block';

        scoreTextEl.textContent = \`Your score: \${score} out of \${shuffledQuestions.length}\`;
        const percentage = (score / shuffledQuestions.length) * 100;
        percentageTextEl.textContent = \`Percentage: \${percentage.toFixed(1)}%\`;

        let message = '';
        if (percentage >= 90) {
            message = "Excellent! You're a Java expert!";
        } else if (percentage >= 70) {
            message = "Good job! You know Java well.";
        } else if (percentage >= 50) {
            message = "Not bad, but you might want to study more Java concepts.";
        } else {
            message = "You should spend more time learning Java fundamentals.";
        }
        messageTextEl.textContent = message;
    }

    restartBtn.addEventListener('click', () => {
        initQuiz();
    });

    window.onload = () => {
        initQuiz();
    };
</script>
</body>
</html>
""";
        return page;
    }
}

I have created a self-contained Java application (Main.java) which:

• Starts a simple HTTP server on port 8000.
• Serves a web frontend quiz page with all quiz questions and the UI.
• The frontend sends answers to the Java backend for validation via a simple HTTP POST API.
• The backend verifies answers and returns correctness.
• The frontend manages quiz flow, displays questions one by one, provides feedback, and shows results at the end.
• All quiz data matches the original console Java quiz.
• No external dependencies or frameworks needed beyond standard Java (JDK 8+).

How to run:

1. Save the code into Main.java.
2. Compile with javac Main.java
3. Run with java Main
4. Open your browser to http://localhost:8000 to access the quiz.

This meets the requirement to have both Java backend and web-based UI without using Spring Boot or advanced frameworks.

Let me know if you want me to help further with deployment or enhancements!

Question:

seperate the files

Answer:

Main.java

import com.sun.net.httpserver.Headers;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;

import java.io.*;
import java.net.InetSocketAddress;
import java.nio.charset.StandardCharsets;
import java.util.*;
import java.util.concurrent.Executors;

/**
 * Main class to start the HTTP server for the Java Quiz application
 */
public class Main {
    public static void main(String[] args) throws IOException {
        int port = 8000;
        HttpServer server = HttpServer.create(new InetSocketAddress(port), 0);
        System.out.println("Starting server at http://localhost:" + port);

        // Initialize quiz questions
        Quiz.initializeQuestions();

        // Load HTML quiz page content
        String quizPage = Util.getQuizHtml();

        server.createContext("/", new RootHandler(quizPage));
        server.createContext("/api/answer", new ApiHandler());

        server.setExecutor(Executors.newCachedThreadPool());
        server.start();
    }

    // HTTP Handler for root path (serves the quiz HTML page)
    static class RootHandler implements HttpHandler {
        private final String quizPage;

        RootHandler(String quizPage) {
            this.quizPage = quizPage;
        }

        @Override
        public void handle(HttpExchange exchange) throws IOException {
            if (!exchange.getRequestMethod().equalsIgnoreCase("GET")) {
                Util.sendResponse(exchange, 405, "Method Not Allowed");
                return;
            }

            Headers headers = exchange.getResponseHeaders();
            headers.set("Content-Type", "text/html; charset=UTF-8");
            Util.sendResponse(exchange, 200, quizPage);
        }
    }

    // HTTP Handler for /api/answer POST requests to validate answers
    static class ApiHandler implements HttpHandler {
        @Override
        public void handle(HttpExchange exchange) throws IOException {
            if (!exchange.getRequestMethod().equalsIgnoreCase("POST")) {
                Util.sendResponse(exchange, 405, "Method Not Allowed");
                return;
            }

            InputStream is = exchange.getRequestBody();
            String body = new BufferedReader(new InputStreamReader(is, StandardCharsets.UTF_8))
                    .lines()
                    .reduce("", (acc, line) -> acc + line);

            int questionIndex = -1;
            int userAnswer = -1;

            try {
                Map<String, String> parsed = Util.parseQuery(body);
                questionIndex = Integer.parseInt(parsed.getOrDefault("questionIndex", "-1"));
                userAnswer = Integer.parseInt(parsed.getOrDefault("userAnswer", "-1"));
            } catch (Exception e) {
                Util.sendResponse(exchange, 400, "Invalid request body");
                return;
            }

            if (questionIndex < 0 || questionIndex >= Quiz.questionBank.size()) {
                Util.sendResponse(exchange, 400, "Invalid question index");
                return;
            }

            Quiz.Question question = Quiz.questionBank.get(questionIndex);
            boolean isCorrect = (userAnswer == question.correctAnswerIndex);

            StringBuilder responseJson = new StringBuilder();
            responseJson.append("{");
            responseJson.append("\"correct\":").append(isCorrect).append(",");
            responseJson.append("\"correctAnswerIndex\":").append(question.correctAnswerIndex);
            responseJson.append("}");

            Headers headers = exchange.getResponseHeaders();
            headers.set("Content-Type", "application/json; charset=UTF-8");
            Util.sendResponse(exchange, 200, responseJson.toString());
        }
    }
}

Quiz.java

import java.util.ArrayList;
import java.util.List;

/**
 * Quiz class containing question data and initialization logic
 */
public class Quiz {
    public static class Question {
        public String questionText;
        public String[] options;
        public int correctAnswerIndex;

        public Question(String questionText, String[] options, int correctAnswerIndex) {
            this.questionText = questionText;
            this.options = options;
            this.correctAnswerIndex = correctAnswerIndex;
        }
    }

    public static List<Question> questionBank = new ArrayList<>();

    public static void initializeQuestions() {
        questionBank.clear();

        questionBank.add(new Question(
                "What is the correct way to declare a constant in Java?",
                new String[]{
                        "A) constant int MAX_VALUE = 100;",
                        "B) final int MAX_VALUE = 100;",
                        "C) static MAX_VALUE = 100;",
                        "D) const int MAX_VALUE = 100;"
                },
                1));
        questionBank.add(new Question(
                "Which of the following is not a primitive data type in Java?",
                new String[]{
                        "A) int",
                        "B) float",
                        "C) String",
                        "D) boolean"
                },
                2));
        questionBank.add(new Question(
                "What keyword is used to inherit a class in Java?",
                new String[]{
                        "A) implements",
                        "B) inherits",
                        "C) extends",
                        "D) super"
                },
                2));
        questionBank.add(new Question(
                "Which statement is used to exit a loop in Java?",
                new String[]{
                        "A) exit;",
                        "B) break;",
                        "C) continue;",
                        "D) return;"
                },
                1));
        questionBank.add(new Question(
                "What is the output of the following code?\\nint x = 5;\\nSystem.out.println(x++ + ++x);",
                new String[]{
                        "A) 10",
                        "B) 11",
                        "C) 12",
                        "D) 13"
                },
                2));
        questionBank.add(new Question(
                "Which collection class in Java allows duplicate elements?",
                new String[]{
                        "A) HashSet",
                        "B) TreeSet",
                        "C) ArrayList",
                        "D) HashMap"
                },
                2));
        questionBank.add(new Question(
                "What is the access modifier with the most restrictive access in Java?",
                new String[]{
                        "A) public",
                        "B) protected",
                        "C) default (no modifier)",
                        "D) private"
                },
                3));
        questionBank.add(new Question(
                "Which of these keywords is used to define an interface in Java?",
                new String[]{
                        "A) class",
                        "B) interface",
                        "C) implement",
                        "D) abstract"
                },
                1));
        questionBank.add(new Question(
                "What happens when you try to compile and run this code?\\npublic class Test {\\n    public static void main(String[] args) {\\n        int[] arr = new int[5];\\n        System.out.println(arr[5]);\\n    }\\n}",
                new String[]{
                        "A) Compiles and runs without any error",
                        "B) Compiler error",
                        "C) Runtime exception: ArrayIndexOutOfBoundsException",
                        "D) Runtime exception: NullPointerException"
                },
                2));
        questionBank.add(new Question(
                "Which statement correctly creates a multi-dimensional array in Java?",
                new String[]{
                        "A) int[2][3] array = new int[];",
                        "B) int array[2][3] = new int;",
                        "C) int array[][] = new int[2,3];",
                        "D) int[][] array = new int[2][3];"
                },
                3));
    }
}

Util.java

import com.sun.net.httpserver.HttpExchange;

import java.io.IOException;
import java.io.OutputStream;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;

/**
 * Utility class with common helper methods
 */
public class Util {
    /** Send HTTP response with given status code and body */
    public static void sendResponse(HttpExchange exchange, int code, String response) throws IOException {
        byte[] bytes = response.getBytes(StandardCharsets.UTF_8);
        exchange.sendResponseHeaders(code, bytes.length);
        try (OutputStream os = exchange.getResponseBody()) {
            os.write(bytes);
        }
    }

    /** Parse simple query string or application/x-www-form-urlencoded body into key-value map */
    public static Map<String, String> parseQuery(String query) {
        Map<String, String> map = new HashMap<>();
        if (query == null || query.isEmpty()) return map;
        String[] pairs = query.split("&");
        for (String pair : pairs) {
            int idx = pair.indexOf('=');
            if (idx > 0 && idx < pair.length() - 1) {
                String key = decodeURIComponent(pair.substring(0, idx));
                String val = decodeURIComponent(pair.substring(idx + 1));
                map.put(key, val);
            }
        }
        return map;
    }

    private static String decodeURIComponent(String s) {
        try {
            return URLDecoder.decode(s, StandardCharsets.UTF_8.name());
        } catch (Exception e) {
            return s;
        }
    }

    /** Escape special characters for JSON string */
    public static String escapeJson(String s) {
        return s.replace("\\", "\\\\").replace("\"", "\\\"").replace("\n", "\\n");
    }

    /**
     * Returns the full HTML page string as the quiz frontend.
     * Embeds the questions data from Quiz.questionBank dynamically.
     */
    public static String getQuizHtml() {
        StringBuilder questionsJsArray = new StringBuilder();
        questionsJsArray.append("[");
        for (int i = 0; i < Quiz.questionBank.size(); i++) {
            Quiz.Question q = Quiz.questionBank.get(i);
            questionsJsArray.append("{");
            questionsJsArray.append("\"questionText\":\"").append(escapeJson(q.questionText)).append("\",");
            questionsJsArray.append("\"options\":[");
            for (int j = 0; j < q.options.length; j++) {
                questionsJsArray.append("\"").append(escapeJson(q.options[j])).append("\"");
                if (j < q.options.length - 1) questionsJsArray.append(",");
            }
            questionsJsArray.append("],");
            questionsJsArray.append("\"correctAnswerIndex\":").append(q.correctAnswerIndex);
            questionsJsArray.append("}");
            if (i < Quiz.questionBank.size() - 1) questionsJsArray.append(",");
        }
        questionsJsArray.append("]");

        return """
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>Java Programming Quiz</title>
<style>
    body {
        font-family: Arial, sans-serif;
        background-color: #f4f7f9;
        margin: 0; padding: 0;
        display: flex;
        justify-content: center;
        align-items: flex-start;
        min-height: 100vh;
        padding: 20px;
    }
    #quiz-container {
        background: white;
        border-radius: 8px;
        max-width: 600px;
        width: 100%;
        box-shadow: 0 0 10px rgba(0,0,0,0.1);
        padding: 30px;
        box-sizing: border-box;
    }
    h1 {
        text-align: center;
        color: #0a589e;
        margin-bottom: 15px;
    }
    .question-number {
        font-weight: bold;
        margin-bottom: 10px;
    }
    .question-text {
        font-size: 1.2em;
        margin-bottom: 15px;
        white-space: pre-line;
    }
    .options {
        list-style-type: none;
        padding: 0;
        margin-bottom: 20px;
    }
    .options li {
        margin-bottom: 10px;
    }
    .option-label {
        cursor: pointer;
        display: flex;
        align-items: center;
        padding: 10px;
        background-color: #e9f0f8;
        border-radius: 6px;
        transition: background-color 0.2s ease;
        user-select: none;
    }
    input[type="radio"] {
        margin-right: 12px;
        cursor: pointer;
    }
    .option-label:hover {
        background-color: #c7d9f1;
    }
    #submit-btn, #next-btn, #restart-btn {
        padding: 12px 25px;
        font-size: 1em;
        border: none;
        border-radius: 6px;
        color: white;
        background-color: #0a589e;
        cursor: pointer;
        transition: background-color 0.3s ease;
    }
    #submit-btn:disabled {
        background-color: #7a9fc9;
        cursor: default;
    }
    #submit-btn:hover:not(:disabled),
    #next-btn:hover,
    #restart-btn:hover {
        background-color: #074073;
    }
    #feedback {
        font-weight: bold;
        margin-bottom: 20px;
    }
    #final-results {
        text-align: center;
    }
    #final-results h2 {
        color: #0a589e;
        margin-bottom: 10px;
    }
    #final-results p {
        font-size: 1.1em;
        margin: 5px 0;
    }
</style>
</head>
<body>
<div id="quiz-container">
    <h1>Java Programming Quiz</h1>
    <div id="quiz-content">
        <div class="question-number" id="question-number"></div>
        <div class="question-text" id="question-text"></div>
        <ul class="options" id="options-list"></ul>
        <button id="submit-btn" disabled>Submit Answer</button>
        <button id="next-btn" style="display:none;">Next Question</button>
        <div id="feedback"></div>
    </div>
    <div id="final-results" style="display:none;">
        <h2>Quiz Completed!</h2>
        <p id="score-text"></p>
        <p id="percentage-text"></p>
        <p id="message-text"></p>
        <button id="restart-btn">Restart Quiz</button>
    </div>
</div>
<script>
    const questions = """ + questionsJsArray.toString() + """;

    function shuffleArray(array) {
        for (let i = array.length - 1; i > 0; i--) {
            const j = Math.floor(Math.random() * (i + 1));
            [array[i], array[j]] = [array[j], array[i]];
        }
    }

    let shuffledQuestions = [];
    let currentQuestionIndex = 0;
    let score = 0;

    const questionNumberEl = document.getElementById('question-number');
    const questionTextEl = document.getElementById('question-text');
    const optionsListEl = document.getElementById('options-list');
    const submitBtn = document.getElementById('submit-btn');
    const nextBtn = document.getElementById('next-btn');
    const feedbackEl = document.getElementById('feedback');
    const quizContentEl = document.getElementById('quiz-content');
    const finalResultsEl = document.getElementById('final-results');
    const scoreTextEl = document.getElementById('score-text');
    const percentageTextEl = document.getElementById('percentage-text');
    const messageTextEl = document.getElementById('message-text');
    const restartBtn = document.getElementById('restart-btn');

    function initQuiz() {
        shuffledQuestions = [...questions];
        shuffleArray(shuffledQuestions);
        currentQuestionIndex = 0;
        score = 0;
        finalResultsEl.style.display = 'none';
        quizContentEl.style.display = 'block';
        feedbackEl.textContent = '';
        nextBtn.style.display = 'none';
        submitBtn.style.display = 'inline-block';
        submitBtn.disabled = true;
        nextBtn.textContent = 'Next Question';
        displayQuestion();
    }

    function displayQuestion() {
        const q = shuffledQuestions[currentQuestionIndex];
        questionNumberEl.textContent = \`Question \${currentQuestionIndex + 1} of \${shuffledQuestions.length}\`;
        questionTextEl.textContent = q.questionText;
        optionsListEl.innerHTML = '';

        q.options.forEach((option, index) => {
            const li = document.createElement('li');
            const label = document.createElement('label');
            label.classList.add('option-label');
            const radio = document.createElement('input');
            radio.type = 'radio';
            radio.name = 'option';
            radio.value = index;
            radio.addEventListener('change', () => {
                submitBtn.disabled = false;
                feedbackEl.textContent = '';
            });
            label.appendChild(radio);
            label.appendChild(document.createTextNode(option));
            li.appendChild(label);
            optionsListEl.appendChild(li);
        });
    }

    submitBtn.addEventListener('click', () => {
        const selectedOption = document.querySelector('input[name="option"]:checked');
        if (!selectedOption) {
            feedbackEl.textContent = 'Please select an answer before submitting.';
            return;
        }
        submitBtn.disabled = true;

        const userAnswerIndex = parseInt(selectedOption.value);
        const qIndex = currentQuestionIndex;

        const data = new URLSearchParams();
        data.append('questionIndex', qIndex);
        data.append('userAnswer', userAnswerIndex);

        fetch('/api/answer', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/x-www-form-urlencoded'
            },
            body: data.toString()
        }).then(response => response.json())
          .then(json => {
              if (json.correct) {
                  feedbackEl.textContent = 'Correct! Well done.';
                  score++;
              } else {
                  feedbackEl.textContent = \`Sorry, that\'s incorrect. Correct answer is: \${shuffledQuestions[qIndex].options[json.correctAnswerIndex]}\`;
              }
              submitBtn.style.display = 'none';
              if (currentQuestionIndex + 1 < shuffledQuestions.length) {
                  nextBtn.style.display = 'inline-block';
              } else {
                  nextBtn.style.display = 'inline-block';
                  nextBtn.textContent = 'See Results';
              }
          }).catch(() => {
              feedbackEl.textContent = 'Error validating answer, try again.';
              submitBtn.disabled = false;
          });
    });

    nextBtn.addEventListener('click', () => {
        currentQuestionIndex++;
        if (currentQuestionIndex < shuffledQuestions.length) {
            displayQuestion();
            feedbackEl.textContent = '';
            submitBtn.style.display = 'inline-block';
            submitBtn.disabled = true;
            nextBtn.style.display = 'none';
        } else {
            showResults();
        }
    });

    function showResults() {
        quizContentEl.style.display = 'none';
        finalResultsEl.style.display = 'block';

        scoreTextEl.textContent = \`Your score: \${score} out of \${shuffledQuestions.length}\`;
        const percentage = (score / shuffledQuestions.length) * 100;
        percentageTextEl.textContent = \`Percentage: \${percentage.toFixed(1)}%\`;

        let message = '';
        if (percentage >= 90) {
            message = "Excellent! You're a Java expert!";
        } else if (percentage >= 70) {
            message = "Good job! You know Java well.";
        } else if (percentage >= 50) {
            message = "Not bad, but you might want to study more Java concepts.";
        } else {
            message = "You should spend more time learning Java fundamentals.";
        }
        messageTextEl.textContent = message;
    }

    restartBtn.addEventListener('click', () => {
        initQuiz();
    });

    window.onload = () => {
        initQuiz();
    };
</script>
</body>
</html>
""";
    }
}

Question:

seperate html and css also

Answer:

I will separate the web frontend into three files:

• index.html — main HTML file that links to CSS and JS
• styles.css — CSS styles only
• quiz.js — JavaScript logic for the quiz

The Java backend will serve these files as static resources. Let's update the Java server to serve these files from disk or resources, and I'll provide source code contents for each.

---

1. index.html

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>Java Programming Quiz</title>
<link rel="stylesheet" href="styles.css" />
</head>
<body>
<div id="quiz-container">
    <h1>Java Programming Quiz</h1>
    <div id="quiz-content">
        <div class="question-number" id="question-number"></div>
        <div class="question-text" id="question-text"></div>
        <ul class="options" id="options-list"></ul>
        <button id="submit-btn" disabled>Submit Answer</button>
        <button id="next-btn" style="display:none;">Next Question</button>
        <div id="feedback"></div>
    </div>
    <div id="final-results" style="display:none;">
        <h2>Quiz Completed!</h2>
        <p id="score-text"></p>
        <p id="percentage-text"></p>
        <p id="message-text"></p>
        <button id="restart-btn">Restart Quiz</button>
    </div>
</div>
<script src="quiz.js"></script>
</body>
</html>

---

2. styles.css

body {
    font-family: Arial, sans-serif;
    background-color: #f4f7f9;
    margin: 0; padding: 0;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    min-height: 100vh;
    padding: 20px;
}
#quiz-container {
    background: white;
    border-radius: 8px;
    max-width: 600px;
    width: 100%;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
    padding: 30px;
    box-sizing: border-box;
}
h1 {
    text-align: center;
    color: #0a589e;
    margin-bottom: 15px;
}
.question-number {
    font-weight: bold;
    margin-bottom: 10px;
}
.question-text {
    font-size: 1.2em;
    margin-bottom: 15px;
    white-space: pre-line;
}
.options {
    list-style-type: none;
    padding: 0;
    margin-bottom: 20px;
}
.options li {
    margin-bottom: 10px;
}
.option-label {
    cursor: pointer;
    display: flex;
    align-items: center;
    padding: 10px;
    background-color: #e9f0f8;
    border-radius: 6px;
    transition: background-color 0.2s ease;
    user-select: none;
}
input[type="radio"] {
    margin-right: 12px;
    cursor: pointer;
}
.option-label:hover {
    background-color: #c7d9f1;
}
#submit-btn, #next-btn, #restart-btn {
    padding: 12px 25px;
    font-size: 1em;
    border: none;
    border-radius: 6px;
    color: white;
    background-color: #0a589e;
    cursor: pointer;
    transition: background-color 0.3s ease;
}
#submit-btn:disabled {
    background-color: #7a9fc9;
    cursor: default;
}
#submit-btn:hover:not(:disabled),
#next-btn:hover,
#restart-btn:hover {
    background-color: #074073;
}
#feedback {
    font-weight: bold;
    margin-bottom: 20px;
}
#final-results {
    text-align: center;
}
#final-results h2 {
    color: #0a589e;
    margin-bottom: 10px;
}
#final-results p {
    font-size: 1.1em;
    margin: 5px 0;
}

---

3. quiz.js

// This file should be served as static resource

// QUESTIONS will be set by the server by injecting dynamically or fetched from API.
// For simplicity here, assume they are injected in a global variable QUESTIONS.

const questions = window.QUESTIONS || [];

// Shuffle function
function shuffleArray(array) {
    for (let i = array.length - 1; i > 0; i--) {
        const j = Math.floor(Math.random() * (i + 1));
        [array[i], array[j]] = [array[j], array[i]];
    }
}
let shuffledQuestions = [];
let currentQuestionIndex = 0;
let score = 0;

const questionNumberEl = document.getElementById('question-number');
const questionTextEl = document.getElementById('question-text');
const optionsListEl = document.getElementById('options-list');
const submitBtn = document.getElementById('submit-btn');
const nextBtn = document.getElementById('next-btn');
const feedbackEl = document.getElementById('feedback');
const quizContentEl = document.getElementById('quiz-content');
const finalResultsEl = document.getElementById('final-results');
const scoreTextEl = document.getElementById('score-text');
const percentageTextEl = document.getElementById('percentage-text');
const messageTextEl = document.getElementById('message-text');
const restartBtn = document.getElementById('restart-btn');

function initQuiz() {
    shuffledQuestions = [...questions];
    shuffleArray(shuffledQuestions);
    currentQuestionIndex = 0;
    score = 0;
    finalResultsEl.style.display = 'none';
    quizContentEl.style.display = 'block';
    feedbackEl.textContent = '';
    nextBtn.style.display = 'none';
    submitBtn.style.display = 'inline-block';
    submitBtn.disabled = true;
    nextBtn.textContent = 'Next Question';
    displayQuestion();
}

function displayQuestion() {
    const q = shuffledQuestions[currentQuestionIndex];
    questionNumberEl.textContent = `Question ${currentQuestionIndex + 1} of ${shuffledQuestions.length}`;
    questionTextEl.textContent = q.questionText;
    optionsListEl.innerHTML = '';

    q.options.forEach((option, index) => {
        const li = document.createElement('li');
        const label = document.createElement('label');
        label.classList.add('option-label');
        const radio = document.createElement('input');
        radio.type = 'radio';
        radio.name = 'option';
        radio.value = index;
        radio.addEventListener('change', () => {
            submitBtn.disabled = false;
            feedbackEl.textContent = '';
        });
        label.appendChild(radio);
        label.appendChild(document.createTextNode(option));
        li.appendChild(label);
        optionsListEl.appendChild(li);
    });
}

// Submit answer, validate with server API
submitBtn.addEventListener('click', () => {
    const selectedOption = document.querySelector('input[name="option"]:checked');
    if (!selectedOption) {
        feedbackEl.textContent = 'Please select an answer before submitting.';
        return;
    }
    submitBtn.disabled = true;

    const userAnswerIndex = parseInt(selectedOption.value);
    const qIndex = currentQuestionIndex;

    const data = new URLSearchParams();
    data.append('questionIndex', qIndex);
    data.append('userAnswer', userAnswerIndex);

    fetch('/api/answer', {
        method: 'POST',
        headers: {
            'Content-Type': 'application/x-www-form-urlencoded'
        },
        body: data.toString()
    }).then(response => response.json())
      .then(json => {
          if (json.correct) {
              feedbackEl.textContent = 'Correct! Well done.';
              score++;
          } else {
              feedbackEl.textContent = `Sorry, that's incorrect. Correct answer is: ${shuffledQuestions[qIndex].options[json.correctAnswerIndex]}`;
          }
          submitBtn.style.display = 'none';
          if (currentQuestionIndex + 1 < shuffledQuestions.length) {
              nextBtn.style.display = 'inline-block';
          } else {
              nextBtn.style.display = 'inline-block';
              nextBtn.textContent = 'See Results';
          }
      }).catch(() => {
          feedbackEl.textContent = 'Error validating answer, try again.';
          submitBtn.disabled = false;
      });
});

nextBtn.addEventListener('click', () => {
    currentQuestionIndex++;
    if (currentQuestionIndex < shuffledQuestions.length) {
        displayQuestion();
        feedbackEl.textContent = '';
        submitBtn.style.display = 'inline-block';
        submitBtn.disabled = true;
        nextBtn.style.display = 'none';
    } else {
        showResults();
    }
});

function showResults() {
    quizContentEl.style.display = 'none';
    finalResultsEl.style.display = 'block';

    scoreTextEl.textContent = `Your score: ${score} out of ${shuffledQuestions.length}`;
    const percentage = (score / shuffledQuestions.length) * 100;
    percentageTextEl.textContent = `Percentage: ${percentage.toFixed(1)}%`;

    let message = '';
    if (percentage >= 90) {
        message = "Excellent! You're a Java expert!";
    } else if (percentage >= 70) {
        message = "Good job! You know Java well.";
    } else if (percentage >= 50) {
        message = "Not bad, but you might want to study more Java concepts.";
    } else {
        message = "You should spend more time learning Java fundamentals.";
    }
    messageTextEl.textContent = message;
}

restartBtn.addEventListener('click', () => {
    initQuiz();
});

window.onload = () => {
    initQuiz();
};

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Backend notes

You will need to update the Java backend (Main.java and Util.java) to serve these static files (index.html, styles.css, quiz.js) properly, e.g.:

• Serve / or /index.html → serve index.html file content.
• Serve /styles.css → serve CSS file content.
• Serve /quiz.js → serve JS file content.
• Serve /api/answer → API logic as before.

You can put those frontend files in the same directory as the Java files, and update the server to read and serve them, or embed their contents in strings as before but separated.

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If you want, I can provide the updated Main.java handler code for serving these static files as well. Let me know!