Question

I would like to to understand how the output works here from this java code..
kindly help !
I took this code from a book called Head First Java
here is the code:

public class EchoTestDrive {

    public static void main(String[] args) {
        Echo e1 = new Echo();
        Echo e2 = new Echo(); // the correct answer
        //or
        Echo e2 = e1; // is the bonus answer!
        int x = 0;
        while (x < 4) {
            e1.hello();
            e1.count = e1.count + 1;
            if (x == 3) {
                e2.count = e2.count + 1;
            }
            if (x > 0) {
                e2.count = e2.count + e1.count;
            }
            x = x + 1;
        }
        System.out.println(e2.count);
    }
}

class Echo {

    int count = 0;

    void hello() {
        System.out.println("helloooo... ");
    }
}

and this is the output:

  %java EchoTestDrive
   helloooo...
   helloooo...
   helloooo...
   helloooo...
   10

Answer 1

Well….

helloooo... being output 4 times is from…

    while (x < 4) {
        e1.hello();
        x = x + 1;
    }

As for the count to 10, (assuming Echo e2 = e1; is meant to be Echo e3 = e1;…

After iteration x = 0: e1.count == 1, e2.count == 0;

After iteration x = 1: e1.count == 2, e2.count == 2;

After iteration x = 2: e1.count == 3, e2.count == 5;

After iteration x = 3: e1.count == 4, e2.count == 10;

Though that interpretation leaves e3 completely unused.