Variable scope and lifetime: Correct Solution

Given the following code:

public class Ienced {
    public void ufmal(int au) {
        int pha = 0;
        A
        se += au;
        pi += au;
        pha += au;
        System.out.println("se=" + se + "  pi=" + pi + "  pha=" + pha);
    }

    private int se = 0;

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

    private static int pi = 0;
}
  1. What does the main method print?
  2. Which of the variables [pha, se, pi, i0, i1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    pha=1  se=1  pi=1
pha=10  se=11  pi=10
pha=100  se=111  pi=100
pha=1010  se=1111  pi=1000

  2. In scope at A : se, pha, pi

  3. In scope at B : se, i0

  4. In scope at C : se, i0, i1

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

  1. se is a static variable, pha is an instance variable, and pi is a local variable.

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

  3. At B , i1 is out of scope because it is not declared yet. pha is out of scope because it is an instance variable, but main is a static method. pi is out of scope because it is local to ufmal.

  4. At C , pha is out of scope because it is an instance variable, but main is a static method. pi is out of scope because it is local to ufmal.

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