Changing values in method that affect variables in main

Question

I am trying to create code that validates a number. If the number is lower than 10 or higher than 20, the value of the number will be changed to 15.

Here is the code:

public class test {

    public static void main(String[] args) {
        int number;
        Scanner input = new Scanner(System.in);
        System.out.print("Enter Number: ");
        number = input.nextInt();
        validateNumber(number);
        System.out.println(number);

    }

    public static int validateNumber(int number) {
        if (number < 10 || number > 20) {
            number = 15;
        }
        return number;
    }
}

The change in the method doesn't do anything in the main method.

Answer 1

You have two ways to do this:

1. Direct printing with function call :

int number;
    Scanner input = new Scanner(System.in);
    System.out.print("Enter Number: ");
    number = input.nextInt();
    System.out.println(validateNumber(number));

2. Storage in a variable, then using it:

int number;
    Scanner input = new Scanner(System.in);
    System.out.print("Enter Number: ");
    number = input.nextInt();
    
    int output = validateNumber(number);
    System.out.println(output);

Answer 2

You already return an Integer. so just do:

number = validateNumber(number);

Thus it will override the number with the return value of the function.

Answer 3

easy-peasy, japanesey!

number = validateNumber(number);