Variable scope and lifetime: Correct Solution

Given the following code:

public class BicRarrad {
    public static void main(String[] args) {
        A
        BicRarrad b0 = new BicRarrad();
        BicRarrad b1 = new BicRarrad();
        B
        b0.fesda(1);
        b0 = new BicRarrad();
        b1.fesda(10);
        b0.fesda(100);
        b1 = b0;
        b1.fesda(1000);
    }

    public void fesda(int ol) {
        int i = 0;
        C
        i += ol;
        id += ol;
        ed += ol;
        System.out.println("i=" + i + "  id=" + id + "  ed=" + ed);
    }

    private int id = 0;
    private static int ed = 0;
}
  1. What does the main method print?
  2. Which of the variables [ed, i, id, b0, b1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    ed=1  i=1  id=1
ed=10  i=10  id=11
ed=100  i=100  id=111
ed=1000  i=1100  id=1111

  2. In scope at A : id, b0

  3. In scope at B : id, b0, b1

  4. In scope at C : id, i, ed

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

  1. id is a static variable, i is an instance variable, and ed is a local variable.

  2. At A , b1 is out of scope because it is not declared yet. i is out of scope because it is an instance variable, but main is a static method. ed is out of scope because it is local to fesda.

  3. At B , i is out of scope because it is an instance variable, but main is a static method. ed is out of scope because it is local to fesda.

  4. At C , b0 and b1 out of scope because they are local to the main method.

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