Random Math Quiz program with Java

Question

I am trying to create a random math quiz program (numbers are supposed to be between 0 and 20 ).

However, when the correct answer is given the program just terminates. How can I fix this?

import java.util.Scanner;

public class Project03 {

    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        System.out.print("Enter your name:");
        String name = keyboard.nextLine();
        System.out.print("Welcome " + name + "! Please answer the following questions:");

        int randomNumber1 =  (int)(20 * Math.random()) + 1;
        int randomNumber2 =  (int)(20 * Math.random()) + 1;
        int randomNumberAdd = randomNumber1 + randomNumber2;
        int randomNumberMul = randomNumber1 * randomNumber2;
        int randomNumberDiv = randomNumber1 / randomNumber2;
        int randomNumberRem = randomNumber1 % randomNumber2;
        double correct = 0;
        double percentageCorrect = correct * 25;


        System.out.print(randomNumber1 + " + " + randomNumber2 + " = ");
        int GuessRandomNumberAdd = keyboard.nextInt();
        if (GuessRandomNumberAdd == randomNumber1 + randomNumber2) {
            System.out.println("Correct!");
            correct++;
        }
        else {
            System.out.println("Wrong!");
            System.out.println("The correct answer is " + randomNumberAdd);

            System.out.print(randomNumber1 + " * " + randomNumber2 + " = ");
            int GuessRandomNumberMul = keyboard.nextInt();
            if (GuessRandomNumberMul == randomNumber1 * randomNumber2) {
                System.out.println("Correct!");
                correct++;
            }
            else{
                System.out.println("Wrong!");
                System.out.println("The correct answer is " + randomNumberMul);
            }

            System.out.print(randomNumber1 + " / " + randomNumber2 + " = ");
            int GuessRandomNumberDiv = keyboard.nextInt();
            if (GuessRandomNumberDiv == randomNumber1 / randomNumber2) {
                System.out.println("Correct!");
                correct++;
            }
            else{
                System.out.println("Wrong!");
                System.out.println("The correct answer is " + randomNumberMul);


                System.out.print(randomNumber1 + " % " + randomNumber2 + " = ");
                int GuessRandomNumberRem = keyboard.nextInt();
                if (GuessRandomNumberRem == randomNumber1 % randomNumber2) {
                    System.out.println("Correct!");
                    correct++;
                }
                else{
                    System.out.println("Wrong!");
                    System.out.println("The correct answer is " + randomNumberRem);

                    System.out.println("You got " + correct + " correct answers.");

                    System.out.println("That's " + percentageCorrect + "%!");
                }
            }
        }
    }
}

Answer 1

You fix it by not nesting your if statements like you are doing. This is what you do:

give first quiz
if answer is correct {
    print "Correct"
} else {
    print "Wrong"

    give second quiz
    if answer is correct {
        print "Correct"
    } else {
        print "Wrong"

        // and so on

    }

}

This is what you want to do:

give first quiz
if answer is correct {
    print "Correct"
} else {
    print "Wrong"
}

give second quiz
if answer is correct {
    print "Correct"
} else {
    print "Wrong"
}

// and so on

---

Unrelated

If you want two random integers between 0 and 20 , both inclusive, you should do it like this:

Random rnd = new Random();
int randomNumber1 = rnd.nextInt(21); // 0-20
int randomNumber2 = rnd.nextInt(21); // 0-20

Of course, you probably don't want randomNumber2 to be 0 (division by zero error), so maybe 1-20 is better for randomNumber2 :

Random rnd = new Random();
int randomNumber1 = rnd.nextInt(21);     // 0-20
int randomNumber2 = rnd.nextInt(20) + 1; // 1-20

Answer 2

I'm assuming you want the program to continue running until the user decides to exist.

A naive approach is to put mostly everything after the "Welcome" line into a while loop that only terminates if the user enters an termination value, like "exit" or "e" as their answer.

// Enter user name
// post first question
// enter answer or "exit" to exit program
while (input != EXIT_FLAG) {
// evaluate user input, check if correct, accumulate right/wrong scores, post next question...
}
// print % correct
System.exit(1);

Answer 3

Thank you so much! I just fixed the problem. I apologize if I asked something very basic!

import java.util.Scanner;

public class Project03 {

    public static void main(String[] args) {
    Scanner keyboard = new Scanner(System.in);
    System.out.print("Enter your name:");
    String name = keyboard.nextLine();
    System.out.print("Welcome " + name + "! Please answer the following questions:");

    int randomNumber1 =  (int)(20 * Math.random()) + 1;
    int randomNumber2 =  (int)(20 * Math.random()) + 1;
    int randomNumberAdd = randomNumber1 + randomNumber2;
    int randomNumberMul = randomNumber1 * randomNumber2;
    int randomNumberDiv = randomNumber1 / randomNumber2;
    int randomNumberRem = randomNumber1 % randomNumber2;
    int correct = 0;


    System.out.print(randomNumber1 + " + " + randomNumber2 + " = ");
    int GuessRandomNumberAdd = keyboard.nextInt();

    if (GuessRandomNumberAdd == randomNumber1 + randomNumber2) {
    System.out.println("Correct!");
    correct++;
  }else {
    System.out.println("Wrong!");
    System.out.println("The correct answer is " + randomNumberAdd);

  }
    System.out.print(randomNumber1 + " * " + randomNumber2 + " = ");    
    int GuessRandomNumberMul = keyboard.nextInt();

  if (GuessRandomNumberMul == randomNumber1 * randomNumber2) {
      System.out.println("Correct!");
      correct++;
  }else{
        System.out.println("Wrong!");
        System.out.println("The correct answer is " + randomNumberMul);


  }
    System.out.print(randomNumber1 + " / " + randomNumber2 + " = ");
    int GuessRandomNumberDiv = keyboard.nextInt();

    if (GuessRandomNumberDiv == randomNumber1 / randomNumber2) {
        System.out.println("Correct!");
        correct++;

        }else{
            System.out.println("Wrong!");
            System.out.println("The correct answer is " + randomNumberMul);


    }
        System.out.print(randomNumber1 + " % " + randomNumber2 + " = ");
        int GuessRandomNumberRem = keyboard.nextInt();
            if (GuessRandomNumberRem == randomNumber1 % randomNumber2) {
            System.out.println("Correct!");
            correct++;

            }else{
                System.out.println("Wrong!");
                System.out.println("The correct answer is " + randomNumberRem);
            }
double percentageCorrect = correct * 25;

System.out.println("You got " + correct + " correct answers.");

System.out.println("That's " + percentageCorrect + "%!");
        }
}

Answer 4

import java.util.Scanner;

public class Project03 {


    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        System.out.print("Enter your name:");
        String name = keyboard.nextLine();
        System.out.print("Welcome " + name + "! Please answer the following questions:");


        double correct = 0;


        for(int i=0; i<10; i++)    {
            int randomNumber1 =  (int)(20 * Math.random()) + 1;
            int randomNumber2 =  (int)(20 * Math.random()) + 1;
            int randomNumberAdd = randomNumber1 + randomNumber2;

            System.out.print(randomNumber1 + " + " + randomNumber2 + " = ");
            int GuessRandomNumberAdd = keyboard.nextInt();
            if (GuessRandomNumberAdd == randomNumber1 + randomNumber2)
            {
                System.out.println("Correct!");
                correct++;
            }
            else
            {
                System.out.println("Wrong!");
                System.out.println("The correct answer is " + randomNumberAdd);

                System.out.print(randomNumber1 + " + " + randomNumber2 + " = ");
                int GuessRandomNumberMul = keyboard.nextInt();
                if (GuessRandomNumberMul == randomNumber1 + randomNumber2) {
                    System.out.println("Correct!");
                    correct++;
                }
                else{
                    System.out.println("Wrong!");
                    System.out.println("The correct answer is " + randomNumberAdd);
                }
            }
        }
        double percentageCorrect = (correct * 100)/10;
        System.out.println("The percentage is " + percentageCorrect);
    }
}