Variable scope and lifetime: Correct Solution

Given the following code:

public class EroBaner {
    public static void main(String[] args) {
        A
        EroBaner e0 = new EroBaner();
        EroBaner e1 = new EroBaner();
        B
        e0.sorkel(1);
        e1.sorkel(10);
        e0.sorkel(100);
        e1 = e0;
        e0 = e1;
        e1.sorkel(1000);
    }

    public void sorkel(int pe) {
        int te = 0;
        C
        te += pe;
        nuo += pe;
        pu += pe;
        System.out.println("te=" + te + "  nuo=" + nuo + "  pu=" + pu);
    }

    private static int pu = 0;
    private int nuo = 0;
}
  1. What does the main method print?
  2. Which of the variables [pu, te, nuo, e0, e1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    pu=1  te=1  nuo=1
pu=10  te=10  nuo=11
pu=100  te=101  nuo=111
pu=1000  te=1101  nuo=1111

  2. In scope at A : nuo, e0

  3. In scope at B : nuo, e0, e1

  4. In scope at C : nuo, te, pu

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

  1. nuo is a static variable, te is an instance variable, and pu is a local variable.

  2. At A , e1 is out of scope because it is not declared yet. te is out of scope because it is an instance variable, but main is a static method. pu is out of scope because it is local to sorkel.

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

  4. At C , e0 and e1 out of scope because they are local to the main method.

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