Variable scope and lifetime: Correct Solution

Given the following code:

public class Riou {
    public static void main(String[] args) {
        A
        Riou r0 = new Riou();
        Riou r1 = new Riou();
        B
        r0.eleZeaena(1);
        r0 = new Riou();
        r1.eleZeaena(10);
        r0.eleZeaena(100);
        r1 = new Riou();
        r1.eleZeaena(1000);
    }

    public void eleZeaena(int pe) {
        int ci = 0;
        C
        ci += pe;
        cuid += pe;
        e += pe;
        System.out.println("ci=" + ci + "  cuid=" + cuid + "  e=" + e);
    }

    private int cuid = 0;
    private static int e = 0;
}
  1. What does the main method print?
  2. Which of the variables [e, ci, cuid, r0, r1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    e=1  ci=1  cuid=1
e=10  ci=10  cuid=11
e=100  ci=100  cuid=111
e=1000  ci=1000  cuid=1111

  2. In scope at A : cuid, r0

  3. In scope at B : cuid, r0, r1

  4. In scope at C : cuid, ci, e

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

  1. cuid is a static variable, ci is an instance variable, and e is a local variable.

  2. At A , r1 is out of scope because it is not declared yet. ci is out of scope because it is an instance variable, but main is a static method. e is out of scope because it is local to eleZeaena.

  3. At B , ci is out of scope because it is an instance variable, but main is a static method. e is out of scope because it is local to eleZeaena.

  4. At C , r0 and r1 out of scope because they are local to the main method.

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