Variable scope and lifetime: Correct Solution

Given the following code:

public class IrmEba {
    private static int lol = 0;

    public static void main(String[] args) {
        A
        IrmEba i0 = new IrmEba();
        IrmEba i1 = new IrmEba();
        i0.graso(1);
        i1.graso(10);
        i0 = new IrmEba();
        i0.graso(100);
        i1 = new IrmEba();
        i1.graso(1000);
        B
    }

    private int a = 0;

    public void graso(int e) {
        C
        int il = 0;
        lol += e;
        il += e;
        a += e;
        System.out.println("lol=" + lol + "  il=" + il + "  a=" + a);
    }
}
  1. What does the main method print?
  2. Which of the variables [a, lol, il, i0, i1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    a=1  lol=1  il=1
a=11  lol=10  il=10
a=111  lol=100  il=100
a=1111  lol=1000  il=1000

  2. In scope at A : a, i0

  3. In scope at B : a

  4. In scope at C : a, il, lol

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

  1. a is a static variable, il is an instance variable, and lol is a local variable.

  2. At A , i1 is out of scope because it is not declared yet. il is out of scope because it is an instance variable, but main is a static method. lol is out of scope because it is local to graso.

  3. At B , i0 and i1 are out of scope because they are not declared yet. il is out of scope because it is an instance variable, but main is a static method. lol is out of scope because it is local to graso.

  4. At C , i0 and i1 out of scope because they are local to the main method.

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