Variable scope and lifetime: Correct Solution

Given the following code:

public class Lispesm {
    private static int er = 0;
    private int to = 0;

    public void flani(int hiul) {
        int e = 0;
        er += hiul;
        to += hiul;
        e += hiul;
        System.out.println("er=" + er + "  to=" + to + "  e=" + e);
        A
    }

    public static void main(String[] args) {
        B
        Lispesm l0 = new Lispesm();
        Lispesm l1 = new Lispesm();
        C
        l0.flani(1);
        l1.flani(10);
        l0.flani(100);
        l1 = new Lispesm();
        l0 = l1;
        l1.flani(1000);
    }
}
  1. What does the main method print?
  2. Which of the variables [e, er, to, l0, l1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    e=1  er=1  to=1
e=11  er=10  to=10
e=111  er=101  to=100
e=1111  er=1000  to=1000

  2. In scope at A : e, er

  3. In scope at B : e, l0

  4. In scope at C : e, l0, l1

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

  1. e is a static variable, er is an instance variable, and to is a local variable.

  2. At A , to is out of scope because it is not declared yet. l0 and l1 out of scope because they are local to the main method.

  3. At B , l1 is out of scope because it is not declared yet. er is out of scope because it is an instance variable, but main is a static method. to is out of scope because it is local to flani.

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

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