Question

Starting codes:

MathQuiz.java

import java.util.Scanner;

public class MathQuiz {

    private final int NUMBER_OF_QUESTIONS = 10;

    private final MathQuestion[] questions = new MathQuestion[NUMBER_OF_QUESTIONS];

    private final int[] userAnswers = new int[NUMBER_OF_QUESTIONS];

    public static void main(String[] args) {

        MathQuiz app = new MathQuiz();

        System.out.println(app.welcomeAndInstructions());

        app.createQuiz();

        app.administerQuiz();

        app.gradeQuiz();

    }

    private String welcomeAndInstructions() {

        return "Welcome to Math Quiz!\n" +

               "There are currently six types of math questions possible:\n" +

               "Addition, Subtraction, Multiplication, Exponents, Division, and Modulo.\n" +

               "The answer to each question will always be an integer.\n\n" +

               "Good luck!\n";

    }

    private void createQuiz() {

        int i = 0;

        OperationType op;

        while (i < NUMBER_OF_QUESTIONS) {

            op = OperationType.getRandom();

            switch (op) {

                case ADD:

                    questions[i++] = new AdditionQuestion();

                    break;

                case SUBTRACT:

                    questions[i++] = new SubtractionQuestion();

                    break;

                case MULTIPLY:

                    questions[i++] = new MultiplicationQuestion();

                    break;

                case EXPONENT:

                    questions[i++] = new ExponentQuestion();

                    break;

                case DIVIDE:

                    questions[i++] = new DivisionQuestion();

                    break;

                case MODULO:

                    questions[i++] = new ModuloQuestion();

                    break;

                default:

                    throw new IllegalArgumentException();

            }

        }

    }

    private void administerQuiz() {

        Scanner scanner = new Scanner(System.in);

        int questionNum = 1;

        for (MathQuestion q : questions) { //POLYMORPHISM!!

            System.out.printf("Question %2d:  %s ", questionNum, q.getQuestion());

            userAnswers[questionNum - 1] = scanner.nextInt();

            questionNum++;

        }

    }

    private void gradeQuiz() {

        int numberCorrect = 0;

        String question;

        int answer;

        System.out.println("\nHere are the correct answers:\n");

        for (int i = 0; i < NUMBER_OF_QUESTIONS; i++) {

            question = questions[i].getQuestion();

            answer = questions[i].getCorrectAnswer();

            System.out.printf("Question number %d:\n    %s\n", i + 1, question);

            System.out.printf("    Correct answer:  %d\n", answer);

            if (userAnswers[i] == answer) {

                System.out.println("    You were CORRECT.");

                numberCorrect++;

            } else {

                System.out.printf("    You said %d, which is INCORRECT.\n", userAnswers[i]);

            }

        }

        System.out.printf("\nYou got %d questions correct.\n", numberCorrect);

        System.out.printf("Your grade on the quiz is %d\n", (numberCorrect * 10));

    }

}

MathQuestion.java

public abstract class MathQuestion implements MathQuestionable {

    // TODO: Declare private member integer constants x and y

    // TODO: Define a default (no parameters) constructor that assigns

    // x to RANDOM.nextInt(MAX_LARGE) + 1

    // y to RANDOM.nextInt(MAX_SMALL) + 1

    // TODO: Define a parameterized constructor that accepts two integer values

    // The first parameter must be assigned to x

    // The second parameter must be assigned to y

    // TODO: Define public accessor methods getX() and getY()

    public String getQuestion(OperationType op) {

        return "What is " + x + ' ' + op.getSymbol() + ' ' + y + '?';

    }

}

class AdditionQuestion extends MathQuestion {

    // A video walk-through will be provided for how to write the code for this class

}

class DivisionQuestion extends MathQuestion {

    private static int _x = RANDOM.nextInt(MAX_LARGE) + 1;

    private static int _y = RANDOM.nextInt(_x) + 1;

    // TODO: Define default constructor to call parent class constructor and passing _x and _y as arguments

    // You will also need to reassign new random values to both _x and _y as shown in the initial assignment statements

    // TODO: Define a parameterized constructor that accepts two integers and passes these in a call to the parent constructor

    // TODO: Define getQuestion that returns a String and makes a call to the parent getQuestion method.

    // You will need to pass OperationType.DIVIDE as the argument

    // TODO: Define getCorrectAnswer that returns an integer result of x / y (this is not as simple as it looks!)

}

class ExponentQuestion extends MathQuestion {

    private static int _x = RANDOM.nextInt(MAX_BASE) + 1;

    private static int _y = RANDOM.nextInt(MAX_EXPONENT);

    // TODO: Define default constructor to call parent class constructor and passing _x and _y as arguments

    // You will also need to reassign new random values to both _x and _y as shown in the initial assignment statements

    // TODO: Define a parameterized constructor that accepts two integers and passes these in a call to the parent constructor

    // TODO: Define getQuestion that returns a String and makes a call to the parent getQuestion method.

    // You will need to pass OperationType.EXPONENT as the argument

    // TODO: Define getCorrectAnswer that returns an integer result of Math.pow(x, y) (this is not as simple as it looks!)

}

class ModuloQuestion extends MathQuestion {

    private static int _x = RANDOM.nextInt(MAX_LARGE) + 1;

    private static int _y = RANDOM.nextInt(_x) + 1;

    // TODO: Define default constructor to call parent class constructor and passing _x and _y as arguments

    // You will also need to reassign new random values to both _x and _y as shown in the initial assignment statements

    // TODO: Define a parameterized constructor that accepts two integers and passes these in a call to the parent constructor

    // TODO: Define getQuestion that returns a String and makes a call to the parent getQuestion method.

    // You will need to pass OperationType.MODULO as the argument

    // TODO: Define getCorrectAnswer that returns an integer result of x % y (this is not as simple as it looks!)

}

class MultiplicationQuestion extends MathQuestion {

    private static int _x = RANDOM.nextInt(MAX_MULTIPLE) + 1;

    private static int _y = RANDOM.nextInt(MAX_MULTIPLE) + 1;

    // TODO: Define default constructor to call parent class constructor and passing _x and _y as arguments

    // You will also need to reassign new random values to both _x and _y as shown in the initial assignment statements

    // TODO: Define a parameterized constructor that accepts two integers and passes these in a call to the parent constructor

    // TODO: Define getQuestion that returns a String and makes a call to the parent getQuestion method.

    // You will need to pass OperationType.MULTIPLY as the argument

    // TODO: Define getCorrectAnswer that returns an integer result of x * y (this is not as simple as it looks!)

}

class SubtractionQuestion extends MathQuestion {

    private static int _x = RANDOM.nextInt(MAX_SMALL) + MAX_SMALL + 1;

    private static int _y = RANDOM.nextInt(MAX_SMALL) + 1;

    // TODO: Define default constructor to call parent class constructor and passing _x and _y as arguments

    // You will also need to reassign new random values to both _x and _y as shown in the initial assignment statements

    // TODO: Define a parameterized constructor that accepts two integers and passes these in a call to the parent constructor

    // TODO: Define getQuestion that returns a String and makes a call to the parent getQuestion method.

    // You will need to pass OperationType.SUBTRACT as the argument

    // TODO: Define getCorrectAnswer that returns an integer result of x - y (this is not as simple as it looks!)

}

MathQuestionable.java

import java.util.Random;

public interface MathQuestionable {

    Random RANDOM = new Random(5); //DO NOT CHANGE THIS LINE

    

   // TODO: Add properties and method headers

}

OperationType.java

import java.util.Random;

public enum OperationType {

    ADD, SUBTRACT, MULTIPLY, EXPONENT, DIVIDE, MODULO;

    private static final Random RANDOM = new Random(5);

    public static OperationType getRandom() {

        OperationType[] values = OperationType.values();

        int length = values.length;

        return values[RANDOM.nextInt(length)];

    }

    public char getSymbol() {

        switch (this) {

            case ADD:

                return '+';

            case SUBTRACT:

                return '-';

            case MULTIPLY:

                return '*';

            case EXPONENT:

                return '^';

            case DIVIDE:

                return '/';

            case MODULO:

                return '%';

            default:

                throw new IllegalArgumentException();

        }

    }

}