CODEWITHSUNDEEP
javaexceptiontry-catch
LtMuffin
LtMuffin

Reputation: 219

Quitting while program is running when user presses 'q' then 'ENTER'

I want to give the user a choice to quit the program while the program is running whenever they feel like it. E.g. Press Q and ENTER at anytime to quit and end program.

I have a try and catch method but whenever I press Q and ENTER, it just displays whats in the catch part.

Here is the code:

public static void partB() {
    //Code for partB goes here.
    //Continues on with partA but with few changes
    /* The number of multiplication problems should not be fixed. Instead, 
       the program should keep posing new multiplication problems until the user decides to quit by entering the letter "q".
       The program should be able to deal with invalid input by the user. 
       It should ignore such input and restate the current multiplication problem.
    */                  
    //Uses the imported Random function.
            Random num = new Random();
            //Initialises the minimum and maximum numbers.
            int minNumber = 10; //Minimum number to start random
            int maxNumber = 20; //Maximum number to start random
            int counter = 0; //Counts the number of questions answered.
            int correctAnswers = 0; //Counts the number of correct answers given.
            final int numberOfQuestions = 0;

            while(numberOfQuestions >= 0) {             
            //Generates a random integer between 10 and 20.
                    int randInt1 = (num.nextInt(maxNumber - minNumber) + minNumber);
                    //Repeats for the 2nd integer to get the product of the two numbers.
                    int randInt2 = (num.nextInt(maxNumber - minNumber) + minNumber);

            //Initialise the Scanner function.
            Scanner input = new Scanner(System.in);

            //Output the Question.
            System.out.println("What is " + randInt1 + " X " + randInt2 + "?" + " " + "(Press 'q' and  ENTER to quit)");
            //Waits for user input.
            try {
            int userInput = input.nextInt();
            String quit = input.nextLine();
            //If user input is 'q', quit program.
            if(quit.equalsIgnoreCase("q")) {
                System.out.println("Exiting...");
                System.exit(0);
            } else {

            int answer = randInt1 * randInt2;
            //Checks if the users input is correct.
                if (answer == userInput) {
                    System.out.println("That is correct!");
                    correctAnswers++;
                }
                else {
                    System.out.println("That is incorrect! " + "The correct answer should be " + answer);
                    counter++;
                }
            }

            } catch(InputMismatchException e) {
                System.out.println("You have entered something other than an integer or 'q'! Please try again with a different question!");

        }
    }
}

Upvotes: 0

Views: 227

Answers (1)

Ian Mc
Ian Mc

Reputation: 5829

If you want to accept both a number and a letter, it is better to use nextLine(). First you check for q, and then parse to number, as follows (note that parseInt will throw a NumberFormatException):

try {
    String userInput = input.nextLine();
    // If user input is 'q', quit program.
    if (userInput.equalsIgnoreCase("q")) {
        System.out.println("Exiting...");
        System.exit(0);
    } else {

        int userAnswer = Integer.parseInt(userInput);
        int answer = randInt1 * randInt2;
        // Checks if the users input is correct.
        if (answer == userAnswer) {
            System.out.println("That is correct!");
            correctAnswers++;
        } else {
            System.out.println("That is incorrect! " + "The correct answer should be " + answer);
            counter++;
        }
    }

} catch (NumberFormatException e) {
    System.out.println(
        "You have entered something other than an integer or 'q'! Please try again with a different question!");

}

Upvotes: 1

Related Questions