Variable scope and lifetime: Correct Solution

Given the following code:

public class Flul {
    private static int ci = 0;

    public void snird(int pid) {
        int e = 0;
        A
        ci += pid;
        ur += pid;
        e += pid;
        System.out.println("ci=" + ci + "  ur=" + ur + "  e=" + e);
    }

    public static void main(String[] args) {
        B
        Flul f0 = new Flul();
        Flul f1 = new Flul();
        C
        f0.snird(1);
        f1 = new Flul();
        f1.snird(10);
        f0 = f1;
        f0.snird(100);
        f1.snird(1000);
    }

    private int ur = 0;
}
  1. What does the main method print?
  2. Which of the variables [e, ci, ur, f0, f1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    e=1  ci=1  ur=1
e=11  ci=10  ur=10
e=111  ci=110  ur=100
e=1111  ci=1110  ur=1000

  2. In scope at A : e, ci, ur

  3. In scope at B : e, f0

  4. In scope at C : e, f0, f1

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

  1. e is a static variable, ci is an instance variable, and ur is a local variable.

  2. At A , f0 and f1 out of scope because they are local to the main method.

  3. At B , f1 is out of scope because it is not declared yet. ci is out of scope because it is an instance variable, but main is a static method. ur is out of scope because it is local to snird.

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

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