Variable scope and lifetime: Correct Solution

Given the following code:

public class OriNentas {
    private static int tood = 0;

    public void zior(int onde) {
        A
        int o = 0;
        ar += onde;
        o += onde;
        tood += onde;
        System.out.println("ar=" + ar + "  o=" + o + "  tood=" + tood);
    }

    private int ar = 0;

    public static void main(String[] args) {
        B
        OriNentas o0 = new OriNentas();
        OriNentas o1 = new OriNentas();
        C
        o0.zior(1);
        o1.zior(10);
        o0 = new OriNentas();
        o1 = new OriNentas();
        o0.zior(100);
        o1.zior(1000);
    }
}
  1. What does the main method print?
  2. Which of the variables [tood, ar, o, o0, o1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    tood=1  ar=1  o=1
tood=10  ar=10  o=11
tood=100  ar=100  o=111
tood=1000  ar=1000  o=1111

  2. In scope at A : o, tood, ar

  3. In scope at B : o, o0

  4. In scope at C : o, o0, o1

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

  1. o is a static variable, tood is an instance variable, and ar is a local variable.

  2. At A , o0 and o1 out of scope because they are local to the main method.

  3. At B , o1 is out of scope because it is not declared yet. tood is out of scope because it is an instance variable, but main is a static method. ar is out of scope because it is local to zior.

  4. At C , tood is out of scope because it is an instance variable, but main is a static method. ar is out of scope because it is local to zior.

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