Variable scope and lifetime: Correct Solution

Given the following code:

public class Mosji {
    public void eshet(int spac) {
        int i = 0;
        i += spac;
        fli += spac;
        ia += spac;
        System.out.println("i=" + i + "  fli=" + fli + "  ia=" + ia);
        A
    }

    private static int ia = 0;
    private int fli = 0;

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

Solution

  1. Output:

    ia=1  i=1  fli=1
ia=10  i=10  fli=11
ia=100  i=100  fli=111
ia=1000  i=1010  fli=1111

  2. In scope at A : fli, i

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

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

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

  1. fli is a static variable, i is an instance variable, and ia is a local variable.

  2. At A , ia is out of scope because it is not declared yet. m0 and m1 out of scope because they are local to the main method.

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

  4. At C , i is out of scope because it is an instance variable, but main is a static method. ia is out of scope because it is local to eshet.

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