Variable scope and lifetime: Correct Solution

Given the following code:

public class Phircflen {
    private static int we = 0;

    public static void main(String[] args) {
        A
        Phircflen p0 = new Phircflen();
        Phircflen p1 = new Phircflen();
        p0.dosae(1);
        p0 = p1;
        p1.dosae(10);
        p1 = new Phircflen();
        p0.dosae(100);
        p1.dosae(1000);
        B
    }

    public void dosae(int ga) {
        int va = 0;
        C
        we += ga;
        va += ga;
        iss += ga;
        System.out.println("we=" + we + "  va=" + va + "  iss=" + iss);
    }

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

Solution

  1. Output:

    iss=1  we=1  va=1
iss=11  we=10  va=10
iss=111  we=100  va=110
iss=1111  we=1000  va=1000

  2. In scope at A : iss, p0

  3. In scope at B : iss

  4. In scope at C : iss, va, we

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

  1. iss is a static variable, va is an instance variable, and we is a local variable.

  2. At A , p1 is out of scope because it is not declared yet. va is out of scope because it is an instance variable, but main is a static method. we is out of scope because it is local to dosae.

  3. At B , p0 and p1 are out of scope because they are not declared yet. va is out of scope because it is an instance variable, but main is a static method. we is out of scope because it is local to dosae.

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

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