In this example of recursion, how come the second printline prints the second half of the output?

Question

I understand how calling the recursion method (n-1) prints out 4 3 2 1, and since on the last one, n=0; it breaks out of the loop I think, however, my lack of understanding comes from how the second print line prints 1 2 3 4.

static void recursion(int n) {
    if(n>0) {
        System.out.println(n);
        recursion(n-1);
        System.out.println(n);
    }
    
}



public static void main(String[] args) {
recursion(4);
}

}

output: 4 3 2 1 1 2 3 4

Answer 1

You call recursion(4)
  which prints 4
  then calls recursion(3)
    which prints 3  
    then calls recursion(2)
      which prints 2
      then calls recursion(1)
        which prints 1
        then calls recursion(0)
          which does nothing
          and returns to the previous level
        which prints 1
        and returns to the previous level
      which prints 2
      and returns to the previous level
    which prints 3
    and returns to the previous level
  which prints 4
  and returns to the previous level
and we're done