Chapter 5 Exercise 2, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

5.2 (Repeat additions) Listing 5.4, SubtractionQuizLoop.java, generates five random subtraction questions. Revise the program to generate ten random addition questions for two integers between 1 and 15. Display the correct count and test time.

import java.util.Scanner;
 
public class ProgrammingEx5_2 {
 public static void main(String[] args) {
  final int NUMBER_OF_QUESTIONS = 10; // Number of questions
  int correctCount = 0; // Count the number of correct answers
  int count = 0; // Count the number of questions
  long startTime = System.currentTimeMillis();
  String output = ""; // output string is initially empty
  Scanner input = new Scanner(System.in);
 
  while (count < NUMBER_OF_QUESTIONS) {
   // 1. Generate two random single-digit integers
   int number1 = (int) (Math.random() * 16);
   int number2 = (int) (Math.random() * 16);
 
   // 3. Prompt the student to answer “What is number1 + number2?”
   System.out.print("What is " + number1 + " + " + number2 + "? ");
   int answer = input.nextInt();
 
   // 4. Grade the answer and display the result
   if (number1 + number2 == answer) {
    System.out.println("You are correct!");
    correctCount++;
   } else
    System.out.println("Your answer is wrong.\n" + number1 + " + "
      + number2 + " should be " + (number1 + number2));
 
   // Increase the count
   count++;
 
   output += "\n" + number1 + " + " + number2 + "=" + answer
     + ((number1 + number2 == answer) ? " correct" : " wrong");
  }
 
  long endTime = System.currentTimeMillis();
  long testTime = endTime - startTime;
 
  System.out.println("Correct count is " + correctCount
    + "\nTest time is " + testTime / 1000 + " seconds\n" + output);
 }
}