How to call a method when there's a string for the user input? (Java)

user12905328 :

What the title says: I'm writing a program where it calculates and shows the sum of the digits in a number (Ex: 3782 sum = 20).

However, I'm having trouble calling the method I used to calculate it back to the main method - it gives me a "java: cannot find symbol" error. I need to use a String for this, and cannot use int for my values.

Here's my code:


public class digitSum {
  //MAIN
    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);

        System.out.println("Please enter a whole number: ");
        String num = input.nextLine();

        //SUM METHOD CALL
           // This is the method call I'm having trouble with.
        printResult(numSum(sum));



    }

  //SUM METHOD
    static void numSum(int i, String num, int sum) {
        for (i = 0; i < num.length(); i++) {
            char a = num.charAt(0);
            char b = num.charAt(i);
            sum = a + b;
        }
        System.out.println("The digit-sum of" +num+ " is: " +sum);
        return;
    }
}

Andronicus :

You've never defined sum variable:

int sum = 0;
printResult(numSum(0, num, sum));

Or even better - why passing accumulator and counter to the function if it's not recursive?

static void numSum(String num) {
    int sum = 0;
    for (int i = 0; i < num.length(); i++) {
        char a = num.charAt(0);
        char b = num.charAt(i);
        sum = a + b;
    }
    System.out.println("The digit-sum of" +num+ " is: " +sum);
    return;
}

Then invoke it by simply calling numSum(num).

P.S.: You also need to have printResult defined (or not - numSum is printing the result).

@chrylis -on strike- notices, that printing the result of your calculation in the caller would be even better:

static int numSum(String num) {
    int sum = 0;
    for (int i = 0; i < num.length(); i++) {
        char a = num.charAt(0);
        char b = num.charAt(i);
        sum = a + b;
    }
    return sum;
}

And in the main method: