Variable scope and lifetime: Correct Solution

Given the following code:

public class Stebo {
    private int ue = 0;
    private static int ve = 0;

    public static void main(String[] args) {
        A
        Stebo s0 = new Stebo();
        Stebo s1 = new Stebo();
        s0.huguss(1);
        s1.huguss(10);
        s0 = s1;
        s0.huguss(100);
        s1 = s0;
        s1.huguss(1000);
        B
    }

    public void huguss(int cuer) {
        int o = 0;
        ve += cuer;
        ue += cuer;
        o += cuer;
        System.out.println("ve=" + ve + "  ue=" + ue + "  o=" + o);
        C
    }
}
  1. What does the main method print?
  2. Which of the variables [o, ve, ue, s0, s1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    o=1  ve=1  ue=1
o=11  ve=10  ue=10
o=111  ve=110  ue=100
o=1111  ve=1110  ue=1000

  2. In scope at A : o, s0

  3. In scope at B : o

  4. In scope at C : o, ve

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

  1. o is a static variable, ve is an instance variable, and ue is a local variable.

  2. At A , s1 is out of scope because it is not declared yet. ve is out of scope because it is an instance variable, but main is a static method. ue is out of scope because it is local to huguss.

  3. At B , s0 and s1 are out of scope because they are not declared yet. ve is out of scope because it is an instance variable, but main is a static method. ue is out of scope because it is local to huguss.

  4. At C , ue is out of scope because it is not declared yet. s0 and s1 out of scope because they are local to the main method.

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