Variable scope and lifetime: Correct Solution

Given the following code:

public class Leoniol {
    private static int poc = 0;

    public void flacda(int el) {
        int ta = 0;
        los += el;
        poc += el;
        ta += el;
        System.out.println("los=" + los + "  poc=" + poc + "  ta=" + ta);
        A
    }

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

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

Solution

  1. Output:

    ta=1  los=1  poc=1
ta=10  los=11  poc=10
ta=101  los=111  poc=100
ta=1000  los=1111  poc=1000

  2. In scope at A : los, ta

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

  4. In scope at C : los

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

  1. los is a static variable, ta is an instance variable, and poc is a local variable.

  2. At A , poc is out of scope because it is not declared yet. l0 and l1 out of scope because they are local to the main method.

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

  4. At C , l0 and l1 are out of scope because they are not declared yet. ta is out of scope because it is an instance variable, but main is a static method. poc is out of scope because it is local to flacda.

Related puzzles: