package hw;
import java.util.Scanner;
import java.util.Random;

public class hw8 {
    public static void main(String[] args) {
        int min = 0;
        int max = 9;
        boolean continueinput = true;
        while (continueinput == true) { //user can use the program without having to run it again.
            int number1 = (int)Math.floor(Math.random() * (max - min + 1) + min);
            int number2 = (int)Math.floor(Math.random() * (max - min + 1) + min);
            Scanner input = new Scanner(System.in);
            System.out.println(number1+" + "+number2+" = ?");
            int studentanswer = input.nextInt();
            int correctanswer = number1 + number2;
            if (studentanswer == correctanswer) {
                System.out.println("Congratulations, you solved it correctly!");
            } else {
                System.out.println("Oh, "+studentanswer+" is not correct, correct answer was "+correctanswer+". But don't worry! I'm sure you'll get it right next time!");
            }
            System.out.println("Do you want to continue solving problems? true(Yes)/false(No) (example: enter false for No)");
            continueinput = input.nextBoolean();
            if (continueinput == false) {
                System.out.println("So you're tired! That's completely okay but don't be a stranger!");
            }
        }
    }
}

For my homework, I am trying to write a math program that can be used by elementary school students. I associated "yes" with true and "no" with false for user to understand. But I don’t think that’s very nice.
Is there any way to run this code when the user types "yes" or "no" directly? Also, if the user types a different value instead of true or false, how can I explain to the user that this is an invalid value and that he/she should enter the value again? I have a little difficulty when it comes to boolean. Thanks in advance.

>Solution :

First of all take care of java naming conventions.
Class names should start with upper case character and all names should be camelCase.
Also for boolean values you can write:

if (continueinput) 

You do not need to write == true it makes it more readable

No to your question:

read the line feed after nextInt() by using nextline
and than you can use

String inputYesNo = input.nextLine();
continueinput = inputYesNo.equalsIgnoreCase("YES") ? true :  false;

to map Yes to true and other values to false

class Hw8 {
    public static void main(String[] args) {
        int min = 0;
        int max = 9;
        boolean continueinput = true;
        while (continueinput) { //user can use the program without having to run it again.
            int number1 = (int) Math.floor(Math.random() * (max - min + 1) + min);
            int number2 = (int) Math.floor(Math.random() * (max - min + 1) + min);
            Scanner input = new Scanner(System.in);
            System.out.println(number1 + " + " + number2 + " = ?");
            int studentanswer = input.nextInt();
            input.nextLine();
            int correctanswer = number1 + number2;
            if (studentanswer == correctanswer) {
                System.out.println("Congratulations, you solved it correctly!");
            } else {
                System.out.println("Oh, " + studentanswer + " is not correct, correct answer was " + correctanswer + ". But don't worry! I'm sure you'll get it right next time!");
            }
            System.out.println("Do you want to continue solving problems? true(Yes)/false(No) (example: enter false for No)");
            String inputYesNo = input.nextLine();
            continueinput = inputYesNo.equalsIgnoreCase("YES") ? true :  false;
            if (!continueinput) {
                System.out.println("So you're tired! That's completely okay but don't be a stranger!");
            }
        }
    }
 }