I made a Java program that did some basic math for kids in primary. I wanted to make it a little more advanced, and remember the questions they got wrong, and then optionally present these questions again at the end and allow them to attempt them once more.
But the code for it got really complicated really quick. I thought I finished it, but it’s having difficulty compiling (read: won’t) and I’m at the point where I need some help. I’d greatly appreciate it.
import java.util.Scanner;
import java.util.Random;
public class ArithmeticTester0 {
public static void main(String[] arg) {
int level = 0;
String type = "";
String name = "";
Scanner keyboard = new Scanner(System.in);
System.out.println("Hi! I am your friendly Math Tutor.");
System.out.print("What is your name? ");
name = keyboard.nextLine();
System.out.print("Would you like to be tested on addition, subtraction or both? ");
type = keyboard.nextLine();
// Check if the type inputted is anything other than addition, subtraction or both
if (!type.equalsIgnoreCase("addition") && !type.equalsIgnoreCase("subtraction") && !type.equalsIgnoreCase("both") && !type.equalsIgnoreCase("add") && !type.equalsIgnoreCase("subtraction")) {
while (!type.equalsIgnoreCase("addition") && !type.equalsIgnoreCase("subtraction") && !type.equalsIgnoreCase("both") && !type.equalsIgnoreCase("add") && !type.equalsIgnoreCase("subtraction")) {
System.out.print("You must answer addition, subtraction or both. How about we try again? ");
type = keyboard.nextLine();
}
}
System.out.print("What level would you like to choose? " +
" Enter 1, 2 or 3: ");
level = keyboard.nextInt();
// Check if the level entered is not 1, 2 or 3
if (level > 3 || level < 1) {
while (level > 3 || level < 1) {
System.out.println("The number must be either 1, 2 or" +
" 3. Let's try again shall we?");
System.out.print("What level would you like to choose? ");
level = keyboard.nextInt();
}
}
System.out.println("\nOK " + name +
", here are 10 exercises for you at level " + level + ".");
System.out.println("Good luck!\n");
int a = 0, b = 0, c = 0;
int preva = 0, prevb = 0; //previous a and b value
int correct = 0;
if (type.equalsIgnoreCase("addition") || type.equalsIgnoreCase("add")) {
add(level, preva, prevb, a, b, c, type);
}
else if (type.equalsIgnoreCase("subtraction") || type.equalsIgnoreCase("subtract")) {
subtract(level, preva, prevb, a, b, c, type);
}
else {
both(level, preva, prevb, a, b, c, type);
}
}
/* The method below prints out a statement depending
on how well the child did */
public static void add(int level, int preva, int prevb, int a, int b, int c, String type) {
Random random = new Random();
Scanner keyboard = new Scanner(System.in);
List<Integer> wrongList = Arrays.asList(array);
int correct = 0;
int wrong = 0;
// Generate 10 questions
for (int i = 1; i <= 10; i++) {
/* Generate numbers depending on the difficulty.
The while loop ensures that the next question isn't the same
as the previous question that was just asked. */
if (level == 1) {
while (preva == a && prevb == b) {
a = random.nextInt(10);
b = random.nextInt(11-a);
}
}
else if (level == 2) {
while (preva == a && prevb == b) {
a = random.nextInt(10);
b = random.nextInt(10);
}
}
else if (level == 3) {
while (preva == a && prevb == b) {
a = random.nextInt(50);
b = random.nextInt(50);
}
}
preva = a;
prevb = b;
System.out.print(a + " + " + b + " = ");
c = keyboard.nextInt();
// Check if the user was correct
if (a + b == c) {
System.out.println("You are right!");
correct++;
}
if (a - b != c) {
wrongList.add(a);
wrongList.add(b);
wrong++;
}
}
// Conclusion
System.out.println("\nYou got " + correct + " right out of 10.");
if (wrong > 0) {
int[] wrongAnswers = wrongList.toArray(new int[wrongList.size()]);
System.out.print("You got " + wrong + " wrong, would you like to retry those questions?");
String response = keyboard.nextLine();
if (response.equalsIgnoreCase("Yes") || response.equalsIgnoreCase("Okay") || response.equalsIgnoreCase("OK") || response.equalsIgnoreCase("Sure") || response.equalsIgnoreCase("Yeah") || response.equalsIgnoreCase("Yea")) {
retry(wrongAnswers, type, wrongIndexArray);
}
else if (response.equalsIgnoreCase("No") || response.equalsIgnoreCase("Nope") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("No thanks") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("Do not want")) {
System.out.println("OK! That's fine.");
}
else {
while (response.equalsIgnoreCase("Yes") || response.equalsIgnoreCase("Okay") || response.equalsIgnoreCase("OK") || response.equalsIgnoreCase("Sure") || response.equalsIgnoreCase("Yeah") || response.equalsIgnoreCase("Yea") || response.equalsIgnoreCase("No") || response.equalsIgnoreCase("Nope") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("No thanks") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("Do not want")) {
System.out.println("Please put in an answer that is along the lines of \"yes\" or \"no\".");
response = keyboard.nextLine();
}
}
}
conclusion(correct, level);
System.out.println("See ya!");
}
public static void subtract(int level, int preva, int prevb, int a, int b, int c, String type) {
Random random = new Random();
Scanner keyboard = new Scanner(System.in);
List<Integer> wrongList = Arrays.asList(array);
// Generate 10 questions
int correct = 0;
int wrong = 0;
for (int i = 1; i <= 10; i++) {
/* Generate numbers depending on the difficulty.
The while loop ensures that the next question isn't the same
as the previous question that was just asked. */
if (level == 1) {
while (preva == a && prevb == b) {
a = random.nextInt(10);
b = random.nextInt(11-a);
while (b > a) {
a = random.nextInt(10);
b = random.nextInt(11-a);
}
}
}
else if (level == 2) {
while (preva == a && prevb == b) {
a = random.nextInt(10);
b = random.nextInt(10);
while (b > a) {
a = random.nextInt(10);
b = random.nextInt(11-a);
}
}
}
else if (level == 3) {
while (preva == a && prevb == b) {
a = random.nextInt(50);
b = random.nextInt(50);
}
}
preva = a;
prevb = b;
System.out.print(a + " - " + b + " = ");
c = keyboard.nextInt();
// Check if the user was correct
if (a - b == c) {
System.out.println("You are right!");
correct++;
}
if (a - b != c) {
wrongList.add(a);
wrongList.add(b);
wrong++;
}
}
// Conclusion
System.out.println("\nYou got " + correct + " right out of 10.");
if (wrong > 0) {
int[] wrongAnswers = wrongList.toArray(new int[wrongList.size()]);
System.out.print("You got " + wrong + " wrong, would you like to retry those questions?");
String response = keyboard.nextLine();
if (response.equalsIgnoreCase("Yes") || response.equalsIgnoreCase("Okay") || response.equalsIgnoreCase("OK") || response.equalsIgnoreCase("Sure") || response.equalsIgnoreCase("Yeah") || response.equalsIgnoreCase("Yea")) {
retry(wrongAnswers, type);
}
else if (response.equalsIgnoreCase("No") || response.equalsIgnoreCase("Nope") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("No thanks") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("Do not want")) {
System.out.println("OK! That's fine.");
}
else {
while (response.equalsIgnoreCase("Yes") || response.equalsIgnoreCase("Okay") || response.equalsIgnoreCase("OK") || response.equalsIgnoreCase("Sure") || response.equalsIgnoreCase("Yeah") || response.equalsIgnoreCase("Yea") || response.equalsIgnoreCase("No") || response.equalsIgnoreCase("Nope") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("No thanks") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("Do not want")) {
System.out.println("Please put in an answer that is along the lines of \"yes\" or \"no\".");
response = keyboard.nextLine();
}
}
}
conclusion(correct, level);
System.out.println("See ya!");
}
public static void both(int level, int preva, int prevb, int a, int b, int c, String type) {
Random random = new Random();
Scanner keyboard = new Scanner(System.in);
// Generate 10 questions
int correct = 0;
List<Integer> wrongIndexes = Arrays.asList(array);
for (int i = 1; i <= 5; i++) {
/* Generate numbers depending on the difficulty.
The while loop ensures that the next question isn't the same
as the previous question that was just asked. */
if (level == 1) {
while (preva == a && prevb == b) {
a = random.nextInt(10);
b = random.nextInt(11-a);
}
}
else if (level == 2) {
while (preva == a && prevb == b) {
a = random.nextInt(10);
b = random.nextInt(10);
}
}
else if (level == 3) {
while (preva == a && prevb == b) {
a = random.nextInt(50);
b = random.nextInt(50);
}
}
preva = a;
prevb = b;
System.out.print(a + " + " + b + " = ");
c = keyboard.nextInt();
// Check if the user was correct
if (a + b == c) {
System.out.println("You are right!");
correct++;
}
else {
System.out.println("Oops! You made a mistake. " + a + " + " + b + " = " + (a+b));
wrongIndexes += i;
}
}
for (int i = 6; i <= 10; i++) {
/* Generate numbers depending on the difficulty.
The while loop ensures that the next question isn't the same
as the previous question that was just asked. */
if (level == 1) {
while (preva == a && prevb == b) {
a = random.nextInt(10);
b = random.nextInt(11-a);
while (b > a) {
a = random.nextInt(10);
b = random.nextInt(11-a);
}
}
}
else if (level == 2) {
while (preva == a && prevb == b) {
a = random.nextInt(10);
b = random.nextInt(10);
while (b > a) {
a = random.nextInt(10);
b = random.nextInt(11-a);
}
}
}
else if (level == 3) {
while (preva == a && prevb == b) {
a = random.nextInt(50);
b = random.nextInt(50);
}
}
preva = a;
prevb = b;
System.out.print(a + " - " + b + " = ");
c = keyboard.nextInt();
// Check if the user was correct
if (a - b == c) {
System.out.println("You are right!");
correct++;
}
else {
System.out.println("Oops! You made a mistake. " + a + " - " + b + " = " + (a-b));
wrongIndexes += i;
}
}
int[] wrongIndexArray = wrongIndexes.toArray(new int[wrongIndexes.size()]);
// Conclusion
System.out.println("\nYou got " + correct + " right out of 10.");
if (wrong > 0) {
int[] wrongAnswers = wrongList.toArray(new int[wrongList.size()]);
System.out.print("You got " + wrong + " wrong, would you like to retry those questions?");
String response = keyboard.nextLine();
if (response.equalsIgnoreCase("Yes") || response.equalsIgnoreCase("Okay") || response.equalsIgnoreCase("OK") || response.equalsIgnoreCase("Sure") || response.equalsIgnoreCase("Yeah") || response.equalsIgnoreCase("Yea")) {
retry(wrongAnswers, type, wrongIndexArray);
}
else if (response.equalsIgnoreCase("No") || response.equalsIgnoreCase("Nope") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("No thanks") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("Do not want")) {
System.out.println("OK! That's fine.");
}
else {
while (response.equalsIgnoreCase("Yes") || response.equalsIgnoreCase("Okay") || response.equalsIgnoreCase("OK") || response.equalsIgnoreCase("Sure") || response.equalsIgnoreCase("Yeah") || response.equalsIgnoreCase("Yea") || response.equalsIgnoreCase("No") || response.equalsIgnoreCase("Nope") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("No thanks") || response.equalsIgnoreCase("Nah") || response.equalsIgnoreCase("Do not want")) {
System.out.println("Please put in an answer that is along the lines of \"yes\" or \"no\".");
response = keyboard.nextLine();
}
}
}
conclusion(correct, level);
System.out.println("See ya!");
}
public static void retry(int[] wrongAnswers, String type, int[] wrongIndexArray) {
int c = 0;
if (type.equalsIgnoreCase("addition") || type.equalsIgnoreCase("add")) {
for (int i = 0; i < wrongAnswers.length; i+=2) {
System.out.print(wrongAnswers[i] + " + " + wrongAnswers[i+1] + " = ");
c = keyboard.nextInt();
if (wrongAnswers[i] + wrongAnswers[i+1] == c) {
System.out.println("You are right!");
}
else {
System.out.println("Oops! You made a mistake. " + wrongIndex[i] + " + " + wrongIndex[i+1] + " = " + (wrongIndex[i]+wrongIndex[i+1]));
}
}
}
else if (type.equalsIgnoreCase("subtraction") || type.equalsIgnoreCase("subtract")) {
for (int i = 0; i < wrongAnswers.length; i+=2) {
System.out.print(wrongAnswers[i] + " - " + wrongAnswers[i+1] + " = ");
c = keyboard.nextInt();
if (wrongAnswers[i] - wrongAnswers[i+1] == c) {
System.out.println("You are right!");
}
else {
System.out.println("Oops! You made a mistake. " + a + " - " + b + " = " + (a-b));
}
}
}
else {
for (int i = 0; i < wrongAnswers.length; i+=2) {
for (int i = 0; i < wrongIndexArray.length; i++) {
if (wrongIndexArray[i] < 6) {
System.out.print(wrongAnswers[i] + " + " + wrongAnswers[i+1] + " = ");
c = keyboard.nextInt();
if (wrongAnswers[i] + wrongAnswers[i+1] == c) {
System.out.println("You are right!");
}
else {
System.out.println("Oops! You made a mistake. " + wrongIndex[i] + " + " + wrongIndex[i+1] + " = " + (wrongIndex[i]+wrongIndex[i+1]));
}
}
else if (wrongIndexArray[i] > 5) {
System.out.print(wrongAnswers[i] + " - " + wrongAnswers[i+1] + " = ");
c = keyboard.nextInt();
if (wrongAnswers[i] - wrongAnswers[i+1] == c) {
System.out.println("You are right!");
}
else {
System.out.println("Oops! You made a mistake. " + wrongIndex[i] + " + " + wrongIndex[i+1] + " = " + (wrongIndex[i]+wrongIndex[i+1]));
}
}
}
}
}
}
public static void conclusion(int x, int lev) {
if (x >= 9) {
if (lev == 3) {
if (x == 9)
System.out.println("Please try the same difficulty again" +
", you almost scored 10 out of 10!");
else
System.out.println("You have mastered addition at this level" +
"! The system is not of any further use.");
}
else {
System.out.println("Please select a higher difficulty next time!");
}
}
else if (x >= 6) {
System.out.println("Please try the test again.");
}
else {
System.out.println("Please ask your teacher for extra lessons.");
}
}
}
The errors are:
You forgot to import java.util.List. Just go ahead and import java.util.*. You know you want to.
You didn’t declare wrongIndexArray, array, wrong, wrongList, keyboard, a, or b anywhere. I may have missed a few.
In this line:
int[] wrongAnswers =wrongList.toArray(new int[wrongList.size()]);wrongList is an
List<Integer>so I think that you can’t cast it to an int[]. You have to use Integer[].Possibly others, but…
…based on the errors you have, are you using an IDE such as NetBeans? Using an IDE will go far in letting you identify the reasons for the errors you’re getting, and they often include helpful hints with each error.
Some other helpful hints:
It looks like you’re storing the operands in a list when the student gets the answer wrong. Consider instead wrapping the operands and the operation into a class such as SubtractionQuestion or AdditionQuestion. It might help later on when you want to retest the student on the ones they got wrong.
Store the “yes” and “no” text answers (Yeah, Yes, Yea, Yup) in an ArrayList<String> yesAnswers, then just check if yesAnswers.contains(answer). This makes it easy to maintain the list, and you also don’t need to check against yes, no, or not yes or no — just check against yes, else no, else bad answer.
Hope that makes sense….