Variable scope and lifetime: Correct Solution

Given the following code:

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

    private int ptur = 0;
    private static int ci = 0;

    public void iste(int ciou) {
        int is = 0;
        is += ciou;
        ptur += ciou;
        ci += ciou;
        System.out.println("is=" + is + "  ptur=" + ptur + "  ci=" + ci);
        C
    }
}
  1. What does the main method print?
  2. Which of the variables [ci, is, ptur, m0, m1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    ci=1  is=1  ptur=1
ci=10  is=10  ptur=11
ci=100  is=100  ptur=111
ci=1000  is=1000  ptur=1111

  2. In scope at A : ptur, m0

  3. In scope at B : ptur, m0, m1

  4. In scope at C : ptur, is

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

  1. ptur is a static variable, is is an instance variable, and ci is a local variable.

  2. At A , m1 is out of scope because it is not declared yet. is is out of scope because it is an instance variable, but main is a static method. ci is out of scope because it is local to iste.

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

  4. At C , ci is out of scope because it is not declared yet. m0 and m1 out of scope because they are local to the main method.

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