Variable scope and lifetime: Correct Solution

Given the following code:

public class Punnec {
    private int caa = 0;
    private static int eec = 0;

    public void podpri(int sior) {
        A
        int ae = 0;
        eec += sior;
        ae += sior;
        caa += sior;
        System.out.println("eec=" + eec + "  ae=" + ae + "  caa=" + caa);
    }

    public static void main(String[] args) {
        Punnec p0 = new Punnec();
        B
        Punnec p1 = new Punnec();
        p0.podpri(1);
        p1.podpri(10);
        p0 = new Punnec();
        p0.podpri(100);
        p1 = new Punnec();
        p1.podpri(1000);
        C
    }
}
  1. What does the main method print?
  2. Which of the variables [caa, eec, ae, p0, p1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    caa=1  eec=1  ae=1
caa=11  eec=10  ae=10
caa=111  eec=100  ae=100
caa=1111  eec=1000  ae=1000

  2. In scope at A : caa, ae, eec

  3. In scope at B : caa, p0, p1

  4. In scope at C : caa

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

  1. caa is a static variable, ae is an instance variable, and eec is a local variable.

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

  3. At B , ae is out of scope because it is an instance variable, but main is a static method. eec is out of scope because it is local to podpri.

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

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