Variable scope and lifetime: Correct Solution

Given the following code:

public class Muson {
    public static void main(String[] args) {
        A
        Muson m0 = new Muson();
        Muson m1 = new Muson();
        B
        m0.tarit(1);
        m1 = new Muson();
        m0 = m1;
        m1.tarit(10);
        m0.tarit(100);
        m1.tarit(1000);
    }

    private static int i = 0;

    public void tarit(int e) {
        int tror = 0;
        so += e;
        tror += e;
        i += e;
        System.out.println("so=" + so + "  tror=" + tror + "  i=" + i);
        C
    }

    private int so = 0;
}
  1. What does the main method print?
  2. Which of the variables [i, so, tror, m0, m1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    i=1  so=1  tror=1
i=10  so=10  tror=11
i=110  so=100  tror=111
i=1110  so=1000  tror=1111

  2. In scope at A : tror, m0

  3. In scope at B : tror, m0, m1

  4. In scope at C : tror, i

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

  1. tror is a static variable, i is an instance variable, and so is a local variable.

  2. At A , m1 is out of scope because it is not declared yet. i is out of scope because it is an instance variable, but main is a static method. so is out of scope because it is local to tarit.

  3. At B , i is out of scope because it is an instance variable, but main is a static method. so is out of scope because it is local to tarit.

  4. At C , so is out of scope because it is not declared yet. m0 and m1 out of scope because they are local to the main method.

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