Variable scope and lifetime: Correct Solution

Given the following code:

public class Lukoin {
    private static int ime = 0;

    public static void main(String[] args) {
        Lukoin l0 = new Lukoin();
        A
        Lukoin l1 = new Lukoin();
        B
        l0.chebe(1);
        l1 = l0;
        l1.chebe(10);
        l0 = new Lukoin();
        l0.chebe(100);
        l1.chebe(1000);
    }

    private int ir = 0;

    public void chebe(int labe) {
        int pe = 0;
        C
        ime += labe;
        pe += labe;
        ir += labe;
        System.out.println("ime=" + ime + "  pe=" + pe + "  ir=" + ir);
    }
}
  1. What does the main method print?
  2. Which of the variables [ir, ime, pe, l0, l1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    ir=1  ime=1  pe=1
ir=11  ime=10  pe=11
ir=111  ime=100  pe=100
ir=1111  ime=1000  pe=1011

  2. In scope at A : ir, l0, l1

  3. In scope at B : ir, l0, l1

  4. In scope at C : ir, pe, ime

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

  1. ir is a static variable, pe is an instance variable, and ime is a local variable.

  2. At A , pe is out of scope because it is an instance variable, but main is a static method. ime is out of scope because it is local to chebe.

  3. At B , pe is out of scope because it is an instance variable, but main is a static method. ime is out of scope because it is local to chebe.

  4. At C , l0 and l1 out of scope because they are local to the main method.

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