Variable scope and lifetime: Correct Solution

Given the following code:

public class Uncis {
    private int tru = 0;
    private static int u = 0;

    public void mepOuril(int od) {
        A
        int mi = 0;
        mi += od;
        tru += od;
        u += od;
        System.out.println("mi=" + mi + "  tru=" + tru + "  u=" + u);
    }

    public static void main(String[] args) {
        B
        Uncis u0 = new Uncis();
        Uncis u1 = new Uncis();
        u0.mepOuril(1);
        u1.mepOuril(10);
        u0.mepOuril(100);
        u0 = new Uncis();
        u1 = new Uncis();
        u1.mepOuril(1000);
        C
    }
}
  1. What does the main method print?
  2. Which of the variables [u, mi, tru, u0, u1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    u=1  mi=1  tru=1
u=10  mi=10  tru=11
u=100  mi=101  tru=111
u=1000  mi=1000  tru=1111

  2. In scope at A : tru, mi, u

  3. In scope at B : tru, u0

  4. In scope at C : tru

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

  1. tru is a static variable, mi is an instance variable, and u is a local variable.

  2. At A , u0 and u1 out of scope because they are local to the main method.

  3. At B , u1 is out of scope because it is not declared yet. mi is out of scope because it is an instance variable, but main is a static method. u is out of scope because it is local to mepOuril.

  4. At C , u0 and u1 are out of scope because they are not declared yet. mi is out of scope because it is an instance variable, but main is a static method. u is out of scope because it is local to mepOuril.

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