Variable scope and lifetime: Correct Solution

Given the following code:

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

    private static int weci = 0;

    public void olha(int as) {
        C
        int re = 0;
        re += as;
        mi += as;
        weci += as;
        System.out.println("re=" + re + "  mi=" + mi + "  weci=" + weci);
    }

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

Solution

  1. Output:

    weci=1  re=1  mi=1
weci=10  re=10  mi=11
weci=100  re=110  mi=111
weci=1000  re=1110  mi=1111

  2. In scope at A : mi, m0, m1

  3. In scope at B : mi

  4. In scope at C : mi, re, weci

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

  1. mi is a static variable, re is an instance variable, and weci is a local variable.

  2. At A , re is out of scope because it is an instance variable, but main is a static method. weci is out of scope because it is local to olha.

  3. At B , m0 and m1 are out of scope because they are not declared yet. re is out of scope because it is an instance variable, but main is a static method. weci is out of scope because it is local to olha.

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

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