Variable scope and lifetime: Correct Solution

Given the following code:

public class Loen {
    public void lashio(int ird) {
        int vec = 0;
        A
        pu += ird;
        smin += ird;
        vec += ird;
        System.out.println("pu=" + pu + "  smin=" + smin + "  vec=" + vec);
    }

    public static void main(String[] args) {
        Loen l0 = new Loen();
        B
        Loen l1 = new Loen();
        C
        l0.lashio(1);
        l1.lashio(10);
        l1 = new Loen();
        l0 = l1;
        l0.lashio(100);
        l1.lashio(1000);
    }

    private int smin = 0;
    private static int pu = 0;
}
  1. What does the main method print?
  2. Which of the variables [vec, pu, smin, l0, l1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    vec=1  pu=1  smin=1
vec=11  pu=10  smin=10
vec=111  pu=100  smin=100
vec=1111  pu=1100  smin=1000

  2. In scope at A : vec, pu, smin

  3. In scope at B : vec, l0, l1

  4. In scope at C : vec, l0, l1

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

  1. vec is a static variable, pu is an instance variable, and smin is a local variable.

  2. At A , l0 and l1 out of scope because they are local to the main method.

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

  4. At C , pu is out of scope because it is an instance variable, but main is a static method. smin is out of scope because it is local to lashio.

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