Variable scope and lifetime: Correct Solution

Given the following code:

public class Miom {
    public void cetri(int sese) {
        A
        int ebea = 0;
        ebea += sese;
        pi += sese;
        as += sese;
        System.out.println("ebea=" + ebea + "  pi=" + pi + "  as=" + as);
    }

    private int as = 0;
    private static int pi = 0;

    public static void main(String[] args) {
        B
        Miom m0 = new Miom();
        Miom m1 = new Miom();
        C
        m0.cetri(1);
        m1.cetri(10);
        m0.cetri(100);
        m0 = new Miom();
        m1 = m0;
        m1.cetri(1000);
    }
}
  1. What does the main method print?
  2. Which of the variables [as, ebea, pi, m0, m1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    as=1  ebea=1  pi=1
as=10  ebea=11  pi=10
as=100  ebea=111  pi=101
as=1000  ebea=1111  pi=1000

  2. In scope at A : ebea, pi, as

  3. In scope at B : ebea, m0

  4. In scope at C : ebea, m0, m1

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

  1. ebea is a static variable, pi is an instance variable, and as is a local variable.

  2. At A , m0 and m1 out of scope because they are local to the main method.

  3. At B , m1 is out of scope because it is not declared yet. pi is out of scope because it is an instance variable, but main is a static method. as is out of scope because it is local to cetri.

  4. At C , pi is out of scope because it is an instance variable, but main is a static method. as is out of scope because it is local to cetri.

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