Variable scope and lifetime: Correct Solution

Given the following code:

public class Spuscoft {
    public static void main(String[] args) {
        A
        Spuscoft s0 = new Spuscoft();
        Spuscoft s1 = new Spuscoft();
        B
        s0.desin(1);
        s1.desin(10);
        s0.desin(100);
        s1 = new Spuscoft();
        s0 = s1;
        s1.desin(1000);
    }

    public void desin(int cer) {
        int te = 0;
        ja += cer;
        te += cer;
        somi += cer;
        System.out.println("ja=" + ja + "  te=" + te + "  somi=" + somi);
        C
    }

    private static int ja = 0;
    private int somi = 0;
}
  1. What does the main method print?
  2. Which of the variables [somi, ja, te, s0, s1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    somi=1  ja=1  te=1
somi=11  ja=10  te=10
somi=111  ja=100  te=101
somi=1111  ja=1000  te=1000

  2. In scope at A : somi, s0

  3. In scope at B : somi, s0, s1

  4. In scope at C : somi, te

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

  1. somi is a static variable, te is an instance variable, and ja is a local variable.

  2. At A , s1 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. ja is out of scope because it is local to desin.

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

  4. At C , ja is out of scope because it is not declared yet. s0 and s1 out of scope because they are local to the main method.

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