Variable scope and lifetime: Correct Solution

Given the following code:

public class Gight {
    public static void main(String[] args) {
        A
        Gight g0 = new Gight();
        Gight g1 = new Gight();
        B
        g0.midiom(1);
        g1 = new Gight();
        g0 = g1;
        g1.midiom(10);
        g0.midiom(100);
        g1.midiom(1000);
    }

    public void midiom(int ul) {
        int si = 0;
        C
        prea += ul;
        ceid += ul;
        si += ul;
        System.out.println("prea=" + prea + "  ceid=" + ceid + "  si=" + si);
    }

    private int prea = 0;
    private static int ceid = 0;
}
  1. What does the main method print?
  2. Which of the variables [si, prea, ceid, g0, g1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    si=1  prea=1  ceid=1
si=10  prea=11  ceid=10
si=110  prea=111  ceid=100
si=1110  prea=1111  ceid=1000

  2. In scope at A : prea, g0

  3. In scope at B : prea, g0, g1

  4. In scope at C : prea, si, ceid

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

  1. prea is a static variable, si is an instance variable, and ceid is a local variable.

  2. At A , g1 is out of scope because it is not declared yet. si is out of scope because it is an instance variable, but main is a static method. ceid is out of scope because it is local to midiom.

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

  4. At C , g0 and g1 out of scope because they are local to the main method.

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