Incorrect result after addition within a function

Question

I have a java program that does not return the correct answer and I cannot figure out why. here's the code:

public class hello {
    public static void main(String[] args) {
        int a =5;
        doubleNumbers(a);
        System.out.println(" 5 doubled is:"+a);
    }

    private static void doubleNumbers(int a) {
        a = 5*2;
    }
}

It is my first java program after helloWorld.

Answer 1

Java is pass-by-value, which means that the variables passed to a function are not changed outside of it.

As this is homework I will not show you the solution, but just tell you to return the value of the calculation.

Answer 2

you're not returning anything from your method

change it to

 private static int doubleNumbers(int a) { 
return a * 2; 
 }