Variable scope and lifetime: Correct Solution

Given the following code:

public class Eoutruss {
    private int uto = 0;
    private static int nem = 0;

    public void maji(int caea) {
        A
        int ai = 0;
        ai += caea;
        uto += caea;
        nem += caea;
        System.out.println("ai=" + ai + "  uto=" + uto + "  nem=" + nem);
    }

    public static void main(String[] args) {
        Eoutruss e0 = new Eoutruss();
        B
        Eoutruss e1 = new Eoutruss();
        e0.maji(1);
        e1 = e0;
        e1.maji(10);
        e0 = new Eoutruss();
        e0.maji(100);
        e1.maji(1000);
        C
    }
}
  1. What does the main method print?
  2. Which of the variables [nem, ai, uto, e0, e1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    nem=1  ai=1  uto=1
nem=10  ai=11  uto=11
nem=100  ai=100  uto=111
nem=1000  ai=1011  uto=1111

  2. In scope at A : uto, ai, nem

  3. In scope at B : uto, e0, e1

  4. In scope at C : uto

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

  1. uto is a static variable, ai is an instance variable, and nem is a local variable.

  2. At A , e0 and e1 out of scope because they are local to the main method.

  3. At B , ai is out of scope because it is an instance variable, but main is a static method. nem is out of scope because it is local to maji.

  4. At C , e0 and e1 are out of scope because they are not declared yet. ai is out of scope because it is an instance variable, but main is a static method. nem is out of scope because it is local to maji.

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