Variable scope and lifetime: Correct Solution

Given the following code:

public class Knessmi {
    private int dest = 0;

    public static void main(String[] args) {
        Knessmi k0 = new Knessmi();
        A
        Knessmi k1 = new Knessmi();
        B
        k0.uinred(1);
        k1.uinred(10);
        k0.uinred(100);
        k1 = k0;
        k0 = new Knessmi();
        k1.uinred(1000);
    }

    public void uinred(int ta) {
        int ar = 0;
        ge += ta;
        dest += ta;
        ar += ta;
        System.out.println("ge=" + ge + "  dest=" + dest + "  ar=" + ar);
        C
    }

    private static int ge = 0;
}
  1. What does the main method print?
  2. Which of the variables [ar, ge, dest, k0, k1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    ar=1  ge=1  dest=1
ar=11  ge=10  dest=10
ar=111  ge=101  dest=100
ar=1111  ge=1101  dest=1000

  2. In scope at A : ar, k0, k1

  3. In scope at B : ar, k0, k1

  4. In scope at C : ar, ge

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

  1. ar is a static variable, ge is an instance variable, and dest is a local variable.

  2. At A , ge is out of scope because it is an instance variable, but main is a static method. dest is out of scope because it is local to uinred.

  3. At B , ge is out of scope because it is an instance variable, but main is a static method. dest is out of scope because it is local to uinred.

  4. At C , dest is out of scope because it is not declared yet. k0 and k1 out of scope because they are local to the main method.

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