What goes where in the memory according to following code?

Question

I am trying to understand how java works and I really need to understand the following points:
For each variable r from line 2, r from line 5, n and x in general
1- the lifetime
2- the scope
3- and the visibility section

It would be very kind of you to help a new programmer understand from your experiences and I really appreciate it as I spend days to understand but couldn't be sure and there is no test for that.

The code is the following:
____________________________________________________________________
1 public class Example {
2 private static int r; // this is the first variable r I want to know about
3
4 public static int logTwo (int x) { //I want to know generally about n and x in all positions
5 int r = 0; // this is the second variable r I want to know about
6 while (x > 1) {
7 x = x / 2;
8 r = r + 1;
9 }
10 return r;
11 }
12
13 public static void main ( String [] args ) {
14 int n = Integer . parseInt ( args [0]);
15 r = logTwo (n);
16 System .out. println (r);
17 r = logTwo (n +1);
18 System . out. println (r);
19 }
20 }
____________________________________________________________________
I spent day reading and couldn't figure out the question I asked so
PLEASE DON'T THROW ME LINKS
It would be very nice to explain I'd really Appreciate it
Thanks a lot in advance!

Answer 1

First variable r, its scope spans entire class and is visible in all methods inside the class. But because its private it's not visible outside the class.

Second variable r is a local variable and shadows the one with class scope -> it means that inside the method r refer to the local variable and not the one with class scope.

The local variable r in the method will be destroyed when we exit the method, but the one with class scope will continue to exist.

For method arguments:
The argument x acts like a local variable, so it only exists until method exits.
the variable you pass into the method is a copy of n , and x holds that copy. But because it is a copy and not a reference, any changes to x wont change the value of n outside the method.

Answer 2

Gen2oo thank you so very much.
I am really grateful to you for your help, time, and amazing explanation.
I voted up and I wish if I can vote 100000000000 times up to you.
This is how much I thank you
Have a great day :)