Variable scope and lifetime: Correct Solution

Given the following code:

public class Verkdod {
    private int ic = 0;

    public void nesPorach(int keol) {
        A
        int ress = 0;
        ress += keol;
        enfu += keol;
        ic += keol;
        System.out.println("ress=" + ress + "  enfu=" + enfu + "  ic=" + ic);
    }

    public static void main(String[] args) {
        B
        Verkdod v0 = new Verkdod();
        Verkdod v1 = new Verkdod();
        C
        v0.nesPorach(1);
        v1.nesPorach(10);
        v1 = new Verkdod();
        v0 = v1;
        v0.nesPorach(100);
        v1.nesPorach(1000);
    }

    private static int enfu = 0;
}
  1. What does the main method print?
  2. Which of the variables [ic, ress, enfu, v0, v1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    ic=1  ress=1  enfu=1
ic=10  ress=11  enfu=10
ic=100  ress=111  enfu=100
ic=1000  ress=1111  enfu=1100

  2. In scope at A : ress, enfu, ic

  3. In scope at B : ress, v0

  4. In scope at C : ress, v0, v1

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

  1. ress is a static variable, enfu is an instance variable, and ic is a local variable.

  2. At A , v0 and v1 out of scope because they are local to the main method.

  3. At B , v1 is out of scope because it is not declared yet. enfu is out of scope because it is an instance variable, but main is a static method. ic is out of scope because it is local to nesPorach.

  4. At C , enfu is out of scope because it is an instance variable, but main is a static method. ic is out of scope because it is local to nesPorach.

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