math-learing/src/com/personalproject/model/QuizQuestion.java

package com.personalproject.model;

import java.util.List;

/**
 * Represents a quiz question with multiple choice options.
 */
public final class QuizQuestion {

  private final String questionText;
  private final List<String> options;
  private final int correctAnswerIndex;

  /**
   * Creates a new quiz question.
   *
   * @param questionText       The text of the question
   * @param options            The list of answer options
   * @param correctAnswerIndex The index of the correct answer in the options list
   */
  public QuizQuestion(String questionText, List<String> options, int correctAnswerIndex) {
    if (questionText == null || questionText.trim().isEmpty()) {
      throw new IllegalArgumentException("Question text cannot be null or empty");
    }
    if (options == null || options.size() < 2) {
      throw new IllegalArgumentException("Options must contain at least 2 choices");
    }
    if (correctAnswerIndex < 0 || correctAnswerIndex >= options.size()) {
      throw new IllegalArgumentException("Correct answer index out of bounds");
    }

    this.questionText = questionText;
    this.options = List.copyOf(options); // Immutable copy
    this.correctAnswerIndex = correctAnswerIndex;
  }

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

  /**
   * Gets the list of answer options.
   *
   * @return An unmodifiable list of answer options
   */
  public List<String> getOptions() {
    return options;
  }

  /**
   * Gets the index of the correct answer in the options list.
   *
   * @return The index of the correct answer
   */
  public int getCorrectAnswerIndex() {
    return correctAnswerIndex;
  }

  /**
   * Checks if the given answer index matches the correct answer.
   *
   * @param answerIndex The index of the user's answer
   * @return true if the answer is correct, false otherwise
   */
  public boolean isAnswerCorrect(int answerIndex) {
    return answerIndex == correctAnswerIndex;
  }
}