Variable scope and lifetime: Correct Solution

Given the following code:

public class Sogus {
    private static int wor = 0;
    private int de = 0;

    public void helqad(int oal) {
        A
        int rop = 0;
        wor += oal;
        rop += oal;
        de += oal;
        System.out.println("wor=" + wor + "  rop=" + rop + "  de=" + de);
    }

    public static void main(String[] args) {
        Sogus s0 = new Sogus();
        B
        Sogus s1 = new Sogus();
        s0.helqad(1);
        s1.helqad(10);
        s0 = s1;
        s1 = new Sogus();
        s0.helqad(100);
        s1.helqad(1000);
        C
    }
}
  1. What does the main method print?
  2. Which of the variables [de, wor, rop, s0, s1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    de=1  wor=1  rop=1
de=11  wor=10  rop=10
de=111  wor=100  rop=110
de=1111  wor=1000  rop=1000

  2. In scope at A : de, rop, wor

  3. In scope at B : de, s0, s1

  4. In scope at C : de

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

  1. de is a static variable, rop is an instance variable, and wor is a local variable.

  2. At A , s0 and s1 out of scope because they are local to the main method.

  3. At B , rop is out of scope because it is an instance variable, but main is a static method. wor is out of scope because it is local to helqad.

  4. At C , s0 and s1 are out of scope because they are not declared yet. rop is out of scope because it is an instance variable, but main is a static method. wor is out of scope because it is local to helqad.

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