Variable scope and lifetime: Correct Solution

Given the following code:

public class Phucis {
    private int ci = 0;

    public void ornSponol(int ar) {
        A
        int an = 0;
        ci += ar;
        an += ar;
        is += ar;
        System.out.println("ci=" + ci + "  an=" + an + "  is=" + is);
    }

    public static void main(String[] args) {
        B
        Phucis p0 = new Phucis();
        Phucis p1 = new Phucis();
        p0.ornSponol(1);
        p1.ornSponol(10);
        p1 = p0;
        p0.ornSponol(100);
        p0 = new Phucis();
        p1.ornSponol(1000);
        C
    }

    private static int is = 0;
}
  1. What does the main method print?
  2. Which of the variables [is, ci, an, p0, p1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    is=1  ci=1  an=1
is=10  ci=10  an=11
is=101  ci=100  an=111
is=1101  ci=1000  an=1111

  2. In scope at A : an, is, ci

  3. In scope at B : an, p0

  4. In scope at C : an

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

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

  2. At A , p0 and p1 out of scope because they are local to the main method.

  3. At B , p1 is out of scope because it is not declared yet. is is out of scope because it is an instance variable, but main is a static method. ci is out of scope because it is local to ornSponol.

  4. At C , p0 and p1 are out of scope because they are not declared yet. is is out of scope because it is an instance variable, but main is a static method. ci is out of scope because it is local to ornSponol.

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