Variable scope and lifetime: Correct Solution

Given the following code:

public class Repdud {
    public void grict(int as) {
        A
        int osm = 0;
        joso += as;
        osm += as;
        comi += as;
        System.out.println("joso=" + joso + "  osm=" + osm + "  comi=" + comi);
    }

    private static int comi = 0;
    private int joso = 0;

    public static void main(String[] args) {
        Repdud r0 = new Repdud();
        B
        Repdud r1 = new Repdud();
        C
        r0.grict(1);
        r1.grict(10);
        r0.grict(100);
        r1 = r0;
        r0 = new Repdud();
        r1.grict(1000);
    }
}
  1. What does the main method print?
  2. Which of the variables [comi, joso, osm, r0, r1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    comi=1  joso=1  osm=1
comi=10  joso=10  osm=11
comi=101  joso=100  osm=111
comi=1101  joso=1000  osm=1111

  2. In scope at A : osm, comi, joso

  3. In scope at B : osm, r0, r1

  4. In scope at C : osm, r0, r1

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

  1. osm is a static variable, comi is an instance variable, and joso is a local variable.

  2. At A , r0 and r1 out of scope because they are local to the main method.

  3. At B , comi is out of scope because it is an instance variable, but main is a static method. joso is out of scope because it is local to grict.

  4. At C , comi is out of scope because it is an instance variable, but main is a static method. joso is out of scope because it is local to grict.

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