Math Quiz in Java

Submitted by GeePee on Sunday, May 10, 2015 - 23:37.

Often times, computer programs are used as a study method by educators. In this program, many of the concepts we have gone over thus far are put together to make a working quiz that asks math questions, and returns results on how the user did. For this program, the user is asked how many math questions they would like. It generates random math questions with numbers 1 through 10, and randomly selects between addition, subtraction, multiplication. and division. If the user is right, it will tell them so. If they are wrong, they will be given the correct answer.

import java.util.*;
 
public class math 
{
 
        public static Scanner keyboard = new Scanner(System.in); //declares public scanner object for use in all methods
        
        public static void main(String[] args) //main method which is mainly used for prompt and calling other methods
        {
        
                System.out.print("How many math questions do you want: ");
                int j = keyboard.nextInt();
 
                keyboard.nextLine(); //clears buffer (needed for use of scanner again)
                
                if (j == 0) //conditional checking if j is 0
                {
                    System.out.println("That's no fun!\n");
                    System.exit(0); //closes program
                 }
                    
                if (j < 0) //this conditional is for if the user enters a negative value
                    j = j * -1; //converts negative input to positive to avoid errors
                
                int i = 0; //initializes counter variable, i
                while (i < j) //loop that will run as long as counter is lower than the number input by user
                {
                    randy(); //calls randy method
                    i++; //increments i by 1
                }
                
                finaloutput(); //calls finaloutput method after loop finishes
                
        }
        
        
        public static void randy() //randy method is used for creating random numbers and passing them to calc method
        {
                Random randy1 = new Random(); //declares randy1 as a new random variable
                Random randy2 = new Random(); //declares randy2
                int m = randy1.nextInt(10)+1; //makes m equal to a random number between 1 and 10
                int n = randy1.nextInt(10)+1; //does the same for n
                int o = randy2.nextInt(3); //makes o equal to a random number between 0 and 2 for deciding an operation
 
                calc(m,n,o); //passes the three random values to calc method
        }
        
        public static int numright = 0; //public integers for keeping track of score
        public static int numwrong = 0;
        
        public static void calc(int a, int b, int c) //accepts values passed to it from randy method
        {
                
                double answer = 0; //declares answer variable
                
                if (c == 0) //conditional checking if third random number generated is 0
                {
                    answer = a + b; //answer to upcoming problem
                    System.out.print("What is " + a + " + " + b + ": "); 
                }
                
                if (c == 1) //conditional if random number is 1
                {
                    answer = a - b; //answer is stored in memory
                    System.out.print("What is " + a + " - " + b + ": "); //gives subtraction problem
                }
                
                if (c == 2) //if random number is 2
                {
                    answer = a * b; //answer stored in memory
                    System.out.print("What is " + a + " x " + b + ": "); //multiplication problem
                }
                
                
                double input = keyboard.nextDouble(); 
                
                if (input == answer) //if user's answer is correct
                    {
                    System.out.println("That is correct!\n");
                    numright++; //ups count of numright
                    }
                    
                else //if user is wrong
                    {
                    System.out.println("That is incorrect! The answer is " + answer + "\n");
                    numwrong++; //ups count of numwrong
                    }
                       
        }
        
        public static void finaloutput() 
        {
                double percentage = numright*100 / (numright + numwrong); //finds the percentage of questions answered correctly
                
                System.out.println("The number of questions you answered correctly is " + numright + " and the number you answered incorrectly is " + numwrong + ". The percentage of questions answered correctly is " + percentage + "%.\n");
        }
}

Be sure to take note of comments, as they explain the code as it goes along. Three random numbers are generated for each question. The first two are any numbers 1-10, and the second is any number 0-2 for determining whether it will deal with addition, subtraction, or multiplication. The end of the calc method keeps tally on how many the user got right, and how many they got wrong. When the quiz is finished, the user is told how many they got right and wrong, and gives them a percentage/score.

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