Variable scope and lifetime: Correct Solution

Given the following code:

public class AcoRenhi {
    public void bleGriid(int ce) {
        int ia = 0;
        cle += ce;
        ia += ce;
        pe += ce;
        System.out.println("cle=" + cle + "  ia=" + ia + "  pe=" + pe);
        A
    }

    private int cle = 0;
    private static int pe = 0;

    public static void main(String[] args) {
        AcoRenhi a0 = new AcoRenhi();
        B
        AcoRenhi a1 = new AcoRenhi();
        a0.bleGriid(1);
        a0 = a1;
        a1 = new AcoRenhi();
        a1.bleGriid(10);
        a0.bleGriid(100);
        a1.bleGriid(1000);
        C
    }
}
  1. What does the main method print?
  2. Which of the variables [pe, cle, ia, a0, a1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    pe=1  cle=1  ia=1
pe=10  cle=10  ia=11
pe=100  cle=100  ia=111
pe=1010  cle=1000  ia=1111

  2. In scope at A : ia, pe

  3. In scope at B : ia, a0, a1

  4. In scope at C : ia

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

  1. ia is a static variable, pe is an instance variable, and cle is a local variable.

  2. At A , cle is out of scope because it is not declared yet. a0 and a1 out of scope because they are local to the main method.

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

  4. At C , a0 and a1 are out of scope because they are not declared yet. pe is out of scope because it is an instance variable, but main is a static method. cle is out of scope because it is local to bleGriid.

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