Variable scope and lifetime: Correct Solution

Given the following code:

public class VaaZik {
    public static void main(String[] args) {
        VaaZik v0 = new VaaZik();
        A
        VaaZik v1 = new VaaZik();
        v0.esspel(1);
        v1 = new VaaZik();
        v1.esspel(10);
        v0 = v1;
        v0.esspel(100);
        v1.esspel(1000);
        B
    }

    private static int orni = 0;
    private int is = 0;

    public void esspel(int ed) {
        int tani = 0;
        C
        tani += ed;
        orni += ed;
        is += ed;
        System.out.println("tani=" + tani + "  orni=" + orni + "  is=" + is);
    }
}
  1. What does the main method print?
  2. Which of the variables [is, tani, orni, v0, v1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    is=1  tani=1  orni=1
is=10  tani=11  orni=10
is=100  tani=111  orni=110
is=1000  tani=1111  orni=1110

  2. In scope at A : tani, v0, v1

  3. In scope at B : tani

  4. In scope at C : tani, orni, is

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

  1. tani is a static variable, orni is an instance variable, and is is a local variable.

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

  3. At B , v0 and v1 are out of scope because they are not declared yet. orni is out of scope because it is an instance variable, but main is a static method. is is out of scope because it is local to esspel.

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

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