Variable scope and lifetime: Correct Solution

Given the following code:

public class Goent {
    private int ceb = 0;

    public void ferku(int ru) {
        int bi = 0;
        ceb += ru;
        ac += ru;
        bi += ru;
        System.out.println("ceb=" + ceb + "  ac=" + ac + "  bi=" + bi);
        A
    }

    public static void main(String[] args) {
        B
        Goent g0 = new Goent();
        Goent g1 = new Goent();
        C
        g0.ferku(1);
        g1 = g0;
        g1.ferku(10);
        g0.ferku(100);
        g0 = g1;
        g1.ferku(1000);
    }

    private static int ac = 0;
}
  1. What does the main method print?
  2. Which of the variables [bi, ceb, ac, g0, g1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    bi=1  ceb=1  ac=1
bi=11  ceb=11  ac=10
bi=111  ceb=111  ac=100
bi=1111  ceb=1111  ac=1000

  2. In scope at A : ceb, bi

  3. In scope at B : ceb, g0

  4. In scope at C : ceb, g0, g1

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

  1. ceb is a static variable, bi is an instance variable, and ac is a local variable.

  2. At A , ac is out of scope because it is not declared yet. g0 and g1 out of scope because they are local to the main method.

  3. At B , g1 is out of scope because it is not declared yet. bi is out of scope because it is an instance variable, but main is a static method. ac is out of scope because it is local to ferku.

  4. At C , bi is out of scope because it is an instance variable, but main is a static method. ac is out of scope because it is local to ferku.

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