Quiz.java

public class Quiz {

	public static void main(String[] args) {
		// Question 1
		MultipleChoiceQuestion question1 = new MultipleChoiceQuestion( 
			"Name the most popular programming language used for developing Android Apps.", // question
			"Python", // A
			"Swift", // B
			"Java", // C
			"HTML", // D
			"C++", // E
			"C"); // Correct Answer
		
		// Question 2
		MultipleChoiceQuestion question2 = new MultipleChoiceQuestion( 
			"Name the most popular programming language used for developing iOS Apps.", // question
			"Python", // A
			"Swift", // B
			"Java", // C
			"HTML", // D
			"C++", // E
			"B"); // Correct Answer
		
		// Question 3
		MultipleChoiceQuestion question3 = new MultipleChoiceQuestion( 
			"Name the most popular programming language used in Machine Learning.", // question	
			"Python", // A
			"Swift", // B
			"Java", // C
			"HTML", // D
			"C++", // E		
			"A"); // Correct Answer			
			
		// Question 4
		MultipleChoiceQuestion question4 = new MultipleChoiceQuestion( 
			"Latest programming language used for creating native Android apps apart from Java.", // question	
			"Python", // A
			"Swift", // B
			"Java", // C
			"Kotlin", // D
			"C++", // E		
			"D"); // Correct Answer	
		
		// Question 5
		MultipleChoiceQuestion question5 = new MultipleChoiceQuestion( 
			"Createing native apps for Android and iOS using React", // question	
			"Flutter", // A
			"Swift", // B
			"Java", // C
			"Kotlin", // D
			"Rect Native", // E		
			"E"); // Correct Answer	
		
		// Question 6
		MultipleChoiceQuestion question6 = new MultipleChoiceQuestion( 
			"Google’s UI toolkit for building natively compiled applications for mobile, web, and desktop from a single codebase.", // question	
			"Flutter", // A
			"Swift", // B
			"Java", // C
			"Kotlin", // D
			"Rect Native", // E		
			"A"); // Correct Answer
		
		
		question1.check();
		question2.check();
		question3.check();
		question4.check();
		question5.check();
		question6.check();
		
		// show the summary results
		MultipleChoiceQuestion.showResults();
	}
}

import javax.swing.JOptionPane;

public class MultipleChoiceQuestion {
	
	static int nQuestions = 0;
	static int nCorrect = 0;
	
	String question;
	String correctAnswer;

	MultipleChoiceQuestion(String query, String a, String b, String c, String d, String e, String answer) {
		question = query+"\n"; // Initialize "question" using the "query" parameter followed by each choice parameter, "a"-"e".
		question += "A. "+a+"\n";
		question += "B. "+b+"\n";
		question += "C. "+c+"\n";
		question += "D. "+d+"\n";
		question += "E. "+e+"\n";
		
		correctAnswer = answer.toUpperCase(); // Initialize "correctAnswer" to the parameter "answer". Convert it to upper case
	}
	
	// method that ask a question and return an upper-cased answer
	String ask() {
		String answer = JOptionPane.showInputDialog(question).toUpperCase();
		while (!isValidAnswer(answer)) {
			JOptionPane.showMessageDialog(null,"Invalid answer. Please enter A, B, C, D, or E.");
			answer = ask();
		}
		return answer;
	}
	
	// method that take the question and check the correct answer
	void check() { 
		nQuestions ++; // increment questions
		String answer = ask(); // call the "ask" method with one of its parameters
		if (answer.equals(correctAnswer)) {
			nCorrect ++; // increment correct answers
			JOptionPane.showMessageDialog(null,"Correct!"); // display message for correct answer
		} else {
			JOptionPane.showMessageDialog(null,"Incorrect. The correct answer is " + correctAnswer); // display message for incorrect answer
		}
	}

	// to display the number of questions and correct answers
	static void showResults() {
		// display the number of questions and the number of correct answers using the static member variables
		JOptionPane.showMessageDialog(null, nCorrect + " correct out of " + nQuestions + " questions ");
	}
	
	// helper method to check valid answer
	private boolean isValidAnswer(String answer) {
		if (answer.equals("A") || answer.equals("B") || answer.equals("C") || answer.equals("D") || answer.equals("E")) {
			return true;
		}
		return false;
	}
}