Reference point changed

Question

When the below code outputs 21 is it just outputting the new data or is it changing the data stored at the reference point?

public class MyClass {
public static void main(String[ ] args) {
Person j;
j = new Person("John");
j.setAge(20);
celebrateBirthday(j);
System.out.println(j.getAge());
}
static void celebrateBirthday(Person p) {
p.setAge(p.getAge() + 1);
}
}
//Outputs "21"

Answer 1

You can safely delete this if you got it figured out 👌

Answer 2

cancel this. I see it sets the age after it gets the age! Sorry.