Variable scope and lifetime: Correct Solution

Given the following code:

public class Licttid {
    private int ac = 0;
    private static int stas = 0;

    public void balont(int sa) {
        int pem = 0;
        pem += sa;
        ac += sa;
        stas += sa;
        System.out.println("pem=" + pem + "  ac=" + ac + "  stas=" + stas);
        A
    }

    public static void main(String[] args) {
        Licttid l0 = new Licttid();
        B
        Licttid l1 = new Licttid();
        l0.balont(1);
        l0 = new Licttid();
        l1.balont(10);
        l1 = new Licttid();
        l0.balont(100);
        l1.balont(1000);
        C
    }
}
  1. What does the main method print?
  2. Which of the variables [stas, pem, ac, l0, l1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    stas=1  pem=1  ac=1
stas=10  pem=10  ac=11
stas=100  pem=100  ac=111
stas=1000  pem=1000  ac=1111

  2. In scope at A : ac, pem

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

  4. In scope at C : ac

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

  1. ac is a static variable, pem is an instance variable, and stas is a local variable.

  2. At A , stas 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 , pem is out of scope because it is an instance variable, but main is a static method. stas is out of scope because it is local to balont.

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

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