Variable scope and lifetime: Correct Solution

Given the following code:

public class Tocig {
    public static void main(String[] args) {
        Tocig t0 = new Tocig();
        A
        Tocig t1 = new Tocig();
        t0.qeune(1);
        t1 = new Tocig();
        t1.qeune(10);
        t0.qeune(100);
        t0 = t1;
        t1.qeune(1000);
        B
    }

    private static int ne = 0;
    private int stec = 0;

    public void qeune(int cin) {
        int e = 0;
        C
        ne += cin;
        e += cin;
        stec += cin;
        System.out.println("ne=" + ne + "  e=" + e + "  stec=" + stec);
    }
}
  1. What does the main method print?
  2. Which of the variables [stec, ne, e, t0, t1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    stec=1  ne=1  e=1
stec=11  ne=10  e=10
stec=111  ne=100  e=101
stec=1111  ne=1000  e=1010

  2. In scope at A : stec, t0, t1

  3. In scope at B : stec

  4. In scope at C : stec, e, ne

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

  1. stec is a static variable, e is an instance variable, and ne is a local variable.

  2. At A , e is out of scope because it is an instance variable, but main is a static method. ne is out of scope because it is local to qeune.

  3. At B , t0 and t1 are out of scope because they are not declared yet. e is out of scope because it is an instance variable, but main is a static method. ne is out of scope because it is local to qeune.

  4. At C , t0 and t1 out of scope because they are local to the main method.

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