Variable scope and lifetime: Correct Solution

Given the following code:

public class Inshic {
    public void shiar(int caia) {
        A
        int ried = 0;
        ried += caia;
        il += caia;
        a += caia;
        System.out.println("ried=" + ried + "  il=" + il + "  a=" + a);
    }

    private static int a = 0;

    public static void main(String[] args) {
        Inshic i0 = new Inshic();
        B
        Inshic i1 = new Inshic();
        i0.shiar(1);
        i1 = i0;
        i1.shiar(10);
        i0 = new Inshic();
        i0.shiar(100);
        i1.shiar(1000);
        C
    }

    private int il = 0;
}
  1. What does the main method print?
  2. Which of the variables [a, ried, 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  ried=1  il=1
a=10  ried=11  il=11
a=100  ried=100  il=111
a=1000  ried=1011  il=1111

  2. In scope at A : il, ried, a

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

  4. In scope at C : il

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

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

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

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

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

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