Variable scope and lifetime: Correct Solution

Given the following code:

public class Hecpel {
    public static void main(String[] args) {
        A
        Hecpel h0 = new Hecpel();
        Hecpel h1 = new Hecpel();
        h0.menni(1);
        h1.menni(10);
        h0 = h1;
        h0.menni(100);
        h1 = h0;
        h1.menni(1000);
        B
    }

    private static int as = 0;

    public void menni(int ne) {
        C
        int he = 0;
        as += ne;
        gint += ne;
        he += ne;
        System.out.println("as=" + as + "  gint=" + gint + "  he=" + he);
    }

    private int gint = 0;
}
  1. What does the main method print?
  2. Which of the variables [he, as, gint, h0, h1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    he=1  as=1  gint=1
he=11  as=10  gint=10
he=111  as=110  gint=100
he=1111  as=1110  gint=1000

  2. In scope at A : he, h0

  3. In scope at B : he

  4. In scope at C : he, as, gint

Explanation (which you do not need to write out in your submitted solution):

  1. he is a static variable, as is an instance variable, and gint is a local variable.

  2. At A , h1 is out of scope because it is not declared yet. as is out of scope because it is an instance variable, but main is a static method. gint is out of scope because it is local to menni.

  3. At B , h0 and h1 are out of scope because they are not declared yet. as is out of scope because it is an instance variable, but main is a static method. gint is out of scope because it is local to menni.

  4. At C , h0 and h1 out of scope because they are local to the main method.

Related puzzles: