Thread: Help with Coding School Assignment

I have a school project assignment and the assignment is to create a math "game" that prompts the user for their name, asks them if they want to do addition, subtraction, multiplication or division. Once they select, it picks 2 random integers between 0-10. If they get it correct, it should congratulate them, ask if they want to play again. If they get it wrong, they get 3 chances. At the end of the game when they don't want to play anymore, it is supposed to give them the total problems they did, # right, # wrong, and percentage of them getting it right. We are just learning loops and I'm probably doing something stupid for it not to work. Copying and pasting the code. Apologize for all of the comments, teacher requires them.

import java.util.Scanner;
import java.util.Random;
 
public class MathGameJMB
 
{
	public static void main(String[] args)
	{
		String name;  // hold value for user's name
		int number1;  // hold value of 1st random number
		int number2;  // hold value of 2nd random number
		int choice;  // hold value of menu choice chosen by user
		int guess;  //  hold value for user's guess to math problem
		int remainder;  // hold value for remainder for division problem
		String again = "y"; // hold value for y/n value if user wants to keep playing
		int attempt = 1; // hold value for the attempt number that the user is on
		int answer = 0;  // hold value for the answer to the math problem
		int remainderGuess; // holds value for user's guess of the remainder
		int gamesPlayed = 0;  // Number of games the user has played
		int answersCorrect = 0; // hold value for number of answers the user gets correct
		int answersWrong = 0;  //hold value for number of answers the user gets wrong
		double percentage;  // Percentage of answers the user got correct
 
		// Create a Scanner object for keyboard input.
		Scanner keyboard = new Scanner(System.in);
 
		// Create a Random object to generate random numbers.
		Random rand = new Random();
 
		// Prompt the user to enter their name, then read the input.
		System.out.print("Please enter your name: ");
		name = keyboard.next();
 
		// Echo print the user's name
		System.out.println("Hello " + name + "!" + " Let's play a simple Math game.");
 
		while (again.equalsIgnoreCase("y"))
		{
			System.out.println("1. Addition");
			System.out.println("2. Subtraction");
			System.out.println("3. Multiplication");
			System.out.println("4. Division");
 
			System.out.print("What type of problem would you like to solve? Enter your selection: ");
			choice = keyboard.nextInt();
 
			System.out.println("Okay, let's play! ");
 
			// Get two random integers between 0 and 10.
			number1 = rand.nextInt(10);
			number2 = rand.nextInt(9);
 
			switch (choice) {
 
			case 1:
				System.out.println("The problem is " + number1 + " + " + number2 + ".");
				answer = number1 + number2; 
				break;
 
 
			case 2:
				System.out.println("The problem is " + number1 + " - " + number2 + ".");
				answer = number1 - number2; 
				break;
 
 
			case 3:
				System.out.println("The problem is " + number1 + " - " + number2 + ".");
				answer = number1 * number2; 
				break;
 
 
			case 4:
				System.out.println("The problem is " + number1 + " - " + number2 + ".");
				answer = number1 / number2; 
 
			default:
				System.out.println("Invalid Choice");
			}
 
			while (attempt  <= 3)
			{
				System.out.print("What is your answer? ");
				guess = keyboard.nextInt();
 
				if (choice == 4)
				{
					System.out.print("Enter the remainder: ");
					remainder = number1 % number2;
					remainderGuess = keyboard.nextInt();
 
				if (guess == answer)
				{
					if (choice == 4 && remainder == remainderGuess)
					{				
						System.out.println("Congratulations! You answered correctly!");
					}
					System.out.println("Congratulations! You answered correctly!");
 
				answersCorrect++;
				gamesPlayed++;
				}
				else
				{
					System.out.println("Sorry, that answer is incorrect. Please try again.");
					attempt++;
				}
			}		
			while (attempt >3)
			{
				gamesPlayed++;
				System.out.println("Study a bit more and then please try the game again. Practice makes perfect!");
			}	
 
			System.out.print("Would you like to play again? (Enter Y to continue and N to exit): ");
			again = again = keyboard.next();
		}
      }
 
	  while (again.equalsIgnoreCase("n"))
	  {
		System.out.println("You played the game " + gamesPlayed + " time(s).");
		System.out.println("You were correct " + answersCorrect + " time(s).");
		System.out.println("You were incorrect " + answersWrong + " time(s).");
 
		percentage = (double)answersCorrect / gamesPlayed;
		System.out.println("You got the answer correct " + percentage + "% " + "of the time.");
		System.out.println("Good bye " + name + " ! I hope you'll play again soon!");
		}
   }
}

Please read the Announcement topic that is at the top of each sub-forum to learn how to properly post code. That article will also give pointers on how to ask questions.

The content of your post is actually pretty good, BUT I'm not sure what you need help with. What do you mean "not work?" Please describe which one of the many assignment requirements is not being satisfied by your code. What are the current results? How should they be different?

Thanks for the compliment! I started testing it and here's the first problem I got to. Once I enter my name, pick addition for example then get the problem. I can enter my solution, but once I do it just goes straight to asking me if I want to play again. If I hit y, it just says "What's your answer?".

As far as multiple methods, we haven't gotten to that yet so everything has to be like that.

You're welcome, but please fix the code so that it is posted correctly.

As for the error you describe, many of the Scanner methods take the next token (int, double, etc.) but leave the <enter> or <lf> character entered by the user at the end of the input line, the input buffer. Then, the next Scanner method that is looking for a line of input accepts the <return> remaining in the buffer as the input. This looks to the frustrated programmer as though statements for input are being skipped.

The way to avoid this behavior is to "flush the input buffer" by scanning for a nextLine() after those methods that leave the <enter> in the buffer and throw the result away. For example:

// gathering numeric input
int1 = input.nextInt();
double1 = input.nextDouble();
 
// clearing the input buffer
input.nextLine();
 
// switching to a line of data
String continue = nextLine();

So the "input.nextLine();" segment would go after my code "guess = keyboard.nextInt();"? and after every input that the user gives? Just want to make sure I understand that correct. We haven't covered flushing the buffer yet or anything.

Long story short. If you are reading string data and numerical data with the Scanner class (same scanner object) you should flush the buffer right after your last numerical input. Commonly known as the Scanner Bug (while technically not a bug).

Another work around is to have 1 scanner object for numerical input and another for Strings. I prefer to have 1 and clear the buffer.

Would that fix the error that I'm currently getting? And, I just put the flush right after the nextInt segment right?

--- Update ---

Hopefully this screenshot will help. Even after adding that code in, it still does the same thing.

I posted my new code. The professor went over kind of an outline of how to set it up today, so this is what I've got now. The current error I'm getting when trying to compile is for the section where gamesPlayed and gamesWon are. The error is "cannot find symbol". I'm not sure if it's because they are outside of the loop or what. After that, the only thing I have to edit in, is for the remainder. I left that part out, because I'm not sure how to put it in there without messing it up.

import java.util.Scanner;
import java.util.Random;
 
public class MathGameJMB
{
	public static void main(String[] args)
	{
		// Create a Scanner object for keyboard input.
		Scanner keyboard = new Scanner(System.in);
 
		// Create random object to generate integers
		Random rand = new Random(); 
 
		// Prompt the user to enter their name, then read the input.
		System.out.print("Please enter your name: ");
		String userName = keyboard.next();
 
		// Echo print the user's name
		System.out.println("Hello " + userName + "!" + " Let's play a simple Math game.");
 
		String playAgain = "y";  // initializes variable for the user playing the game
 
		do {
			System.out.println("1. Addition");
			System.out.println("2. Subtraction");
			System.out.println("3. Multiplication");
			System.out.println("4. Division");
 
			System.out.print("From the choices above, what type of problem would you like to solve? Enter your selection: ");
			int choice = keyboard.nextInt();  // initializes & reads the input for the user's choice of type of math problem
 
			System.out.println("Okay, let's play! ");
 
			// Get two random integers between 0 and 10. 
			int number1 = rand.nextInt(10) + 1;
			int number2 = rand.nextInt(10) + 1;
			int answer;  // initialize variable for the calculated answer to the math problem
 
			if (choice == 1) {
				System.out.println("The problem is " + number1 + " + " + number2 + ".");
				answer = number1 + number2; 
			} else if (choice == 2) {
				System.out.println("The problem is " + number1 + " - " + number2 + ".");
				answer = number1 - number2;
			} else if (choice == 3) {
				System.out.println("The problem is " + number1 + " - " + number2 + ".");
				answer = number1 * number2;
			} else if (choice == 4) {
				System.out.println("The problem is " + number1 + " - " + number2 + ".");
				answer = number1 / number2;
			}
 
			final int MAX_TRIES = 3; // Initialize the final value for maxium numnber of tries the user gets
			int tries = 0; // initializing variable for number of tries the user currently has
			int gamesPlayed;  //initialize value for number of games the user has played
			int gamesWon = 0;  // initialize the value for the number of games the user has won
 
			System.out.print("What is your answer? ");
			int guess = keyboard.nextInt();  // initialize the variable for the user's guess
 
			while (tries < MAX_TRIES && guess != answer) {
				tries++;
				System.out.println("Sorry, that answer is incorrect. Please try again.");
			}
 
			if (guess == answer) {
				System.out.println("Congratulations! You answered correctly!");
				gamesWon++;
				gamesPlayed++;
 
			} else {
				System.out.println("Study a bit more and then please try the game again. Practice makes perfect!");
			}
				gamesPlayed++;
 
			System.out.print("Would you like to play again? (Enter Y to continue and N to exit): ");
			playAgain = keyboard.next();
 
		} while (playAgain.equals("y"));
 
		if (playAgain.equals("n")); {
		System.out.println("You played the game " + gamesPlayed + " time(s).");
		System.out.println("You were correct " + gamesWon + " time(s).");
		System.out.println("You were incorrect " + (gamesPlayed - gamesWon) + " time(s).");
 
		percentage = (double)gamesWon / gamesPlayed;  // initialize the variable for the user's winning percentage at the game
		System.out.println("You got the answer correct " + percentage + "% " + "of the time.");
		System.out.println("Good bye " + userName + " ! I hope you'll play again soon!");
		}
	}
}

I got the error fixed and I'm trying to put in the remainder and prompting the user for it if they pick division, but it just skips asking for the remainder and counts it correct if the answer is correct.

import java.util.Scanner;
import java.util.Random;
 
public class MathGameJMB
{
	public static void main(String[] args)
	{
		// Create a Scanner object for keyboard input.
		Scanner keyboard = new Scanner(System.in);
 
		// Create random object to generate integers
		Random rand = new Random(); 
 
		// Prompt the user to enter their name, then read the input.
		System.out.print("Please enter your name: ");
		String userName = keyboard.next();
 
		// Echo print the user's name
		System.out.println("Hello " + userName + "!" + " Let's play a simple Math game.");
 
		String playAgain = "y";  // initializes variable for the user playing the game
		int gamesPlayed = 0;  //initialize value for number of games the user has played
		int gamesWon = 0;  // initialize the value for the number of games the user has won
		int answer = 0;  // initialize variable for the calculated answer to the math problem
		int remainder = 0;  // initialize variable for the remainder of the division problem for the user
 
		do {
			System.out.println("1. Addition");
			System.out.println("2. Subtraction");
			System.out.println("3. Multiplication");
			System.out.println("4. Division");
 
			System.out.print("From the choices above, what type of problem would you like to solve? Enter your selection: ");
			int choice = keyboard.nextInt();  // initializes & reads the input for the user's choice of type of math problem
 
			System.out.println("Okay, let's play! ");
 
			// Get two random integers between 0 and 10. 
			int number1 = rand.nextInt(10) + 1;
			int number2 = rand.nextInt(10) + 1;
 
 
			if (choice == 1) 
			{
				System.out.println("The problem is " + number1 + " + " + number2 + ".");
				answer = number1 + number2; 
			} 
			else if (choice == 2) 
			{
				System.out.println("The problem is " + number1 + " - " + number2 + ".");
				answer = number1 - number2;
			} 
			else if (choice == 3) 
			{
				System.out.println("The problem is " + number1 + " * " + number2 + ".");
				answer = number1 * number2;
			} 
			else if (choice == 4) 
			{
				System.out.println("The problem is " + number1 + " / " + number2 + ".");
				answer = number1 / number2;
				choice = number1 % number2;
			}
 
			final int MAX_TRIES = 3; // Initialize the final value for maxium numnber of tries the user gets
			int tries = 1; // initializing variable for number of tries the user currently has
 
			System.out.print("What is your answer? ");
			int guess = keyboard.nextInt();  // initialize the variable for the user's guess
			int remainderGuess = 0;  // initialize the value and variable for the user's guess at what the remainder is
 
			if (choice == 4)
			{
				System.out.print("Enter the remainder: ");
				remainderGuess = keyboard.nextInt();
			}
 
			while (tries < MAX_TRIES && guess != answer || remainderGuess != remainder) {
				tries++;
				System.out.println("Sorry, that answer is incorrect. Please try again.");
				System.out.print("What is your answer? ");
				guess = keyboard.nextInt();  // record the input for the user's guess
 
				if (choice == 4)
				{
					System.out.print("Enter the remainder: ");
					remainderGuess = keyboard.nextInt();
				}
			}
 
			if (guess == answer)
			{
				if (choice == 4 && remainderGuess == remainder)
				{
					System.out.println("Congratulations! You answered correctly!");
				}
 
				System.out.println("Congratulations! You answered correctly!");
				gamesWon++;
				gamesPlayed++;
			} 
			else
			{
				System.out.println("Study a bit more and then please try the game again. Practice makes perfect!");
				gamesPlayed++;
			}
 
 
 
			System.out.print("Would you like to play again? (Enter Y to continue and N to exit): ");
			playAgain = keyboard.next();
 
		} while (playAgain.equals("y"));
 
		// Once the user has chosen not to play the game again, output how many games they have played, times won, times lost, and winning percentage.
		System.out.println("You played the game " + gamesPlayed + " time(s).");
		System.out.println("You were correct " + gamesWon + " time(s).");
		System.out.println("You were incorrect " + (gamesPlayed - gamesWon) + " time(s).");
 
		double percentage = (double)gamesWon / gamesPlayed * 100;  // initialize the variable for the user's winning percentage at the game
		System.out.println("You got the answer correct " + percentage + "% " + "of the time.");
		System.out.println("Good bye " + userName + " ! I hope you'll play again soon!");
 
		if (percentage >= 90)
		{
			System.out.println("You have excellent math skills!");
		}
		else if (percentage >= 80 && percentage < 90)
		{
			System.out.println("You are doing a great job, but there is room for improvement!");
		}
		else if (percentage < 80 && percentage >= 70)
		{
			System.out.println("You have average math skills.");
		}
		else if (percentage < 70)
		{
			System.out.println("You need more practice in order to improve your math skills.");
		}
	}
}