Variable scope and lifetime: Correct Solution

Given the following code:

public class Icar {
    private int gec = 0;

    public void couSqen(int io) {
        int vec = 0;
        A
        thol += io;
        vec += io;
        gec += io;
        System.out.println("thol=" + thol + "  vec=" + vec + "  gec=" + gec);
    }

    private static int thol = 0;

    public static void main(String[] args) {
        Icar i0 = new Icar();
        B
        Icar i1 = new Icar();
        i0.couSqen(1);
        i1.couSqen(10);
        i0.couSqen(100);
        i1 = i0;
        i0 = new Icar();
        i1.couSqen(1000);
        C
    }
}
  1. What does the main method print?
  2. Which of the variables [gec, thol, vec, i0, i1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    gec=1  thol=1  vec=1
gec=11  thol=10  vec=10
gec=111  thol=100  vec=101
gec=1111  thol=1000  vec=1101

  2. In scope at A : gec, vec, thol

  3. In scope at B : gec, i0, i1

  4. In scope at C : gec

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

  1. gec is a static variable, vec is an instance variable, and thol is a local variable.

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

  3. At B , vec is out of scope because it is an instance variable, but main is a static method. thol is out of scope because it is local to couSqen.

  4. At C , i0 and i1 are out of scope because they are not declared yet. vec is out of scope because it is an instance variable, but main is a static method. thol is out of scope because it is local to couSqen.

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